diff --git a/idl/GCObject.json5 b/idl/GCObject.json5
index 2b0b669..234b3d0 100644
--- a/idl/GCObject.json5
+++ b/idl/GCObject.json5
@@ -6,6 +6,7 @@
     includes: [
         "<xo/alloc2/Allocator.hpp>",
         "<xo/alloc2/Collector.hpp>",
+        "<xo/alloc2/GCObjectVisitor.hpp>",
         "<cstdint>",
         "<cstddef>",
     ],
@@ -42,6 +43,11 @@
             doc: ["fomo collector type"],
             definition: "xo::mm::ACollector",
         },
+        {
+            name: "AGCObjectVisitor",
+            doc: ["fomo collector type"],
+            definition: "xo::mm::AGCObjectVisitor",
+        },
     ],
     const_methods: [
         // size_type shallow_size() const noexcept
@@ -68,13 +74,17 @@
             noexcept: true,
             attributes: [],
         },
-        // size_type forward_children(obj<ACollector>) noexcept
+        // size_type visit_gco_children(obj<AGCObjectVisitor>) noexcept
         {
-            name: "forward_children",
-            doc: ["during GC: forward immdiate children"],
+            name: "visit_gco_children",
+            doc: [
+                "Invoke fn.visit_child(iface,data) for each child GCObject pointer.",
+                "Context: provides address of data pointer so it can be updated in place",
+                "when @p fn invokes garbage collector reentry point"
+            ],
             return_type: "void",
             args: [
-                {type: "obj<ACollector>", name: "gc"},
+                {type: "obj<AGCObjectVisitor>", name: "fn"},
             ],
             const: true,
             noexcept: true,
diff --git a/idl/GCObjectVisitor.json5 b/idl/GCObjectVisitor.json5
index b465842..2e8344d 100644
--- a/idl/GCObjectVisitor.json5
+++ b/idl/GCObjectVisitor.json5
@@ -71,5 +71,26 @@
             attributes: [],
         },
     ],
-    router_facet_explicit_content: []
+    router_facet_explicit_content: [
+        "",
+        "/** visit forward faceted object child pointer in place.",
+        "    Defined in RGCObject.hpp to avoid #include cycle",
+        " **/",
+        "template <typename DRepr>",
+        "void visit_child(xo::facet::obj<AGCObject,DRepr> * p_obj);",
+        "",
+        "/** visit typed child data pointer in place.",
+        "    Defined in RGCObject.hpp to avoid #include cycle",
+        " **/",
+        "template <typename DRepr>",
+        "void visit_child(DRepr ** pp_data);",
+        "",
+        "/** visit faceted object pointer stored using some facet",
+        "    other than AGCObject",
+        " **/",
+        "template <typename AFacet, typename DRepr>",
+        "requires (!std::is_same_v<AFacet, AGCObject>)",
+        "void visit_poly_child(obj<AFacet,DRepr> * p_pivot);",
+        "",
+    ]
 }
diff --git a/include/xo/alloc2/gc/AGCObject.hpp b/include/xo/alloc2/gc/AGCObject.hpp
index b5b9fb0..3c0fed0 100644
--- a/include/xo/alloc2/gc/AGCObject.hpp
+++ b/include/xo/alloc2/gc/AGCObject.hpp
@@ -16,6 +16,7 @@
 // includes (via {facet_includes})
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/alloc2/Collector.hpp>
+#include <xo/alloc2/GCObjectVisitor.hpp>
 #include <cstdint>
 #include <cstddef>
 #include <xo/facet/obj.hpp>
@@ -48,6 +49,8 @@ public:
     using AAllocator = xo::mm::AAllocator;
     /** fomo collector type **/
     using ACollector = xo::mm::ACollector;
+    /** fomo collector type **/
+    using AGCObjectVisitor = xo::mm::AGCObjectVisitor;
     ///@}
 
     /** @defgroup mm-gcobject-methods **/
@@ -66,8 +69,10 @@ public:
     // nonconst methods
     /** move instance using allocator **/
     virtual Opaque shallow_move(Opaque data, obj<ACollector> gc)  const  noexcept = 0;
-    /** during GC: forward immdiate children **/
-    virtual void forward_children(Opaque data, obj<ACollector> gc)  const  noexcept = 0;
+    /** Invoke fn.visit_child(iface,data) for each child GCObject pointer.
+Context: provides address of data pointer so it can be updated in place
+when @p fn invokes garbage collector reentry point **/
+    virtual void visit_gco_children(Opaque data, obj<AGCObjectVisitor> fn)  const  noexcept = 0;
     ///@}
 }; /*AGCObject*/
 
diff --git a/include/xo/alloc2/gc/IGCObject_Any.hpp b/include/xo/alloc2/gc/IGCObject_Any.hpp
index 34f0bca..7f12f82 100644
--- a/include/xo/alloc2/gc/IGCObject_Any.hpp
+++ b/include/xo/alloc2/gc/IGCObject_Any.hpp
@@ -47,6 +47,7 @@ namespace mm {
         using size_type = AGCObject::size_type;
         using AAllocator = AGCObject::AAllocator;
         using ACollector = AGCObject::ACollector;
+        using AGCObjectVisitor = AGCObject::AGCObjectVisitor;
 
         ///@}
         /** @defgroup mm-gcobject-any-methods **/
@@ -64,7 +65,7 @@ namespace mm {
 
         // nonconst methods
         [[noreturn]] Opaque shallow_move(Opaque, obj<ACollector>)  const  noexcept override;
-        [[noreturn]] void forward_children(Opaque, obj<ACollector>)  const  noexcept override;
+        [[noreturn]] void visit_gco_children(Opaque, obj<AGCObjectVisitor>)  const  noexcept override;
 
         ///@}
 
diff --git a/include/xo/alloc2/gc/IGCObject_Xfer.hpp b/include/xo/alloc2/gc/IGCObject_Xfer.hpp
index d69184c..361bc51 100644
--- a/include/xo/alloc2/gc/IGCObject_Xfer.hpp
+++ b/include/xo/alloc2/gc/IGCObject_Xfer.hpp
@@ -15,6 +15,7 @@
 
 #include <xo/alloc2/Allocator.hpp>
 #include <xo/alloc2/Collector.hpp>
+#include <xo/alloc2/GCObjectVisitor.hpp>
 #include <cstdint>
 #include <cstddef>
 
@@ -34,6 +35,7 @@ namespace mm {
         using size_type = AGCObject::size_type;
         using AAllocator = AGCObject::AAllocator;
         using ACollector = AGCObject::ACollector;
+        using AGCObjectVisitor = AGCObject::AGCObjectVisitor;
         ///@}
 
         /** @defgroup mm-gcobject-xfer-methods **/
@@ -54,8 +56,8 @@ namespace mm {
         Opaque shallow_move(Opaque data, obj<ACollector> gc)  const  noexcept override {
             return I::shallow_move(_dcast(data), gc);
         }
-        void forward_children(Opaque data, obj<ACollector> gc)  const  noexcept override {
-            return I::forward_children(_dcast(data), gc);
+        void visit_gco_children(Opaque data, obj<AGCObjectVisitor> fn)  const  noexcept override {
+            return I::visit_gco_children(_dcast(data), fn);
         }
 
         ///@}
diff --git a/include/xo/alloc2/gc/RCollector_aux.hpp b/include/xo/alloc2/gc/RCollector_aux.hpp
index 529f69d..83bc631 100644
--- a/include/xo/alloc2/gc/RCollector_aux.hpp
+++ b/include/xo/alloc2/gc/RCollector_aux.hpp
@@ -17,6 +17,46 @@ namespace xo {
         class ACollector;
         class AGCObject;
 
+        /** defined here to avoid #include cycle, since
+         *  template obj<AGCObject,DRepr> awkward to make available
+         *  in RCollector.hpp
+         **/
+        template <typename Object>
+        template <typename DRepr>
+        void
+        RGCObjectVisitor<Object>::visit_child(xo::facet::obj<AGCObject,DRepr> * p_obj)
+        {
+            this->visit_child(p_obj->iface(), (void **)&(p_obj->data_));
+        }
+
+        template <typename Object>
+        template <typename DRepr>
+        void
+        RGCObjectVisitor<Object>::visit_child(DRepr ** p_repr)
+        {
+            // fetch static interface for DRepr (strip const: FacetImplementation specializations use non-const DRepr)
+            auto iface = xo::facet::impl_for<AGCObject, std::remove_const_t<DRepr>>();
+
+            this->visit_child(&iface, (void **)p_repr);
+        }
+
+        template <typename Object>
+        template <typename AFacet, typename DRepr>
+        requires (!std::is_same_v<AFacet, AGCObject>)
+        void
+        RGCObjectVisitor<Object>::visit_poly_child(obj<AFacet, DRepr> * p_objs)
+        {
+            if (*p_objs) {
+                auto e = xo::facet::FacetRegistry::instance().variant<AGCObject,AFacet>(*p_objs);
+
+                this->visit_child(e.iface(), (void **)&(p_objs->data_));
+            }
+        }
+
+        // ----- DEPRECATED -----
+        //
+        // Moving these methods to RGCObjectVisitor
+
         /** defined here to avoid #include cycle, since
          *  template obj<AGCObject,DRepr> awkward to make available
          *  in RCollector.hpp
@@ -52,6 +92,8 @@ namespace xo {
             }
         }
 
+        // ----- mm_do_assign -----
+
         /** gc-aware assignment; engage special book-keeping for cross-gen pointers **/
         inline void mm_do_assign(obj<ACollector> & gc,
                                  void * parent,
diff --git a/include/xo/alloc2/gc/RGCObject.hpp b/include/xo/alloc2/gc/RGCObject.hpp
index a0de103..5ac4c48 100644
--- a/include/xo/alloc2/gc/RGCObject.hpp
+++ b/include/xo/alloc2/gc/RGCObject.hpp
@@ -34,6 +34,7 @@ public:
     using size_type = AGCObject::size_type;
     using AAllocator = AGCObject::AAllocator;
     using ACollector = AGCObject::ACollector;
+    using AGCObjectVisitor = AGCObject::AGCObjectVisitor;
     ///@}
 
     /** @defgroup mm-gcobject-router-ctors **/
@@ -60,8 +61,8 @@ public:
     Opaque shallow_move(obj<ACollector> gc)  noexcept {
         return O::iface()->shallow_move(O::data(), gc);
     }
-    void forward_children(obj<ACollector> gc)  noexcept {
-        return O::iface()->forward_children(O::data(), gc);
+    void visit_gco_children(obj<AGCObjectVisitor> fn)  noexcept {
+        return O::iface()->visit_gco_children(O::data(), fn);
     }
 
     ///@}
diff --git a/include/xo/alloc2/gc/RGCObjectVisitor.hpp b/include/xo/alloc2/gc/RGCObjectVisitor.hpp
index 800d197..7fbf907 100644
--- a/include/xo/alloc2/gc/RGCObjectVisitor.hpp
+++ b/include/xo/alloc2/gc/RGCObjectVisitor.hpp
@@ -46,6 +46,26 @@ public:
     ///@{
 
     // explicit injected content
+    
+    /** visit forward faceted object child pointer in place.
+        Defined in RGCObject.hpp to avoid #include cycle
+     **/
+    template <typename DRepr>
+    void visit_child(xo::facet::obj<AGCObject,DRepr> * p_obj);
+    
+    /** visit typed child data pointer in place.
+        Defined in RGCObject.hpp to avoid #include cycle
+     **/
+    template <typename DRepr>
+    void visit_child(DRepr ** pp_data);
+    
+    /** visit faceted object pointer stored using some facet
+        other than AGCObject
+     **/
+    template <typename AFacet, typename DRepr>
+    requires (!std::is_same_v<AFacet, AGCObject>)
+    void visit_poly_child(obj<AFacet,DRepr> * p_pivot);
+    
 
     // builtin methods
     typeseq _typeseq() const noexcept { return O::iface()->_typeseq(); }
diff --git a/src/alloc2/IGCObject_Any.cpp b/src/alloc2/IGCObject_Any.cpp
index a441524..7df0548 100644
--- a/src/alloc2/IGCObject_Any.cpp
+++ b/src/alloc2/IGCObject_Any.cpp
@@ -42,7 +42,7 @@ IGCObject_Any::shallow_move(Opaque, obj<ACollector>)  const  noexcept -> Opaque
 }
 
 auto
-IGCObject_Any::forward_children(Opaque, obj<ACollector>)  const  noexcept -> void
+IGCObject_Any::visit_gco_children(Opaque, obj<AGCObjectVisitor>)  const  noexcept -> void
 {
     _fatal();
 }