diff --git a/include/xo/gc/DX1Collector.hpp b/include/xo/gc/DX1Collector.hpp
index b0feefc..a582ed8 100644
--- a/include/xo/gc/DX1Collector.hpp
+++ b/include/xo/gc/DX1Collector.hpp
@@ -274,14 +274,6 @@ namespace xo {
             /** Execute gc immediately, for all generations < @p upto **/
             void execute_gc(Generation upto) noexcept;
 
-            /** Supports GCObjectVisitor facet.
-             *  During gc phase (@p reason is 'forward')
-             *  1. evacuate object at @p *lhs_data to to-space.
-             *  2. replace @p *lhs_data with forwarding pointer
-             *     to new location.
-             **/
-            void visit_child(VisitReason reason, AGCObject * lhs_iface, void ** lhs_data);
-
             // ----- allocation -----
 
             /** simple allocation. allocate @p z bytes of memory
diff --git a/include/xo/gc/GCObjectStore.hpp b/include/xo/gc/GCObjectStore.hpp
index 76b1597..5fdddeb 100644
--- a/include/xo/gc/GCObjectStore.hpp
+++ b/include/xo/gc/GCObjectStore.hpp
@@ -169,37 +169,6 @@ namespace xo {
                                       void * from_src,
                                       Generation upto);
 
-            /** Target for GCObjectVisitor facet
-             *  During gc phase (@p reason is 'forward')
-             *  1. evacuate object at @p *lhs_data to to-space.
-             *  2. replace @p *lhs_data with forwarding pointer
-             *     to new location.
-             **/
-            void visit_child_aux(VisitReason reason,
-                                 AGCObject * lhs_iface,
-                                 void ** lhs_data,
-                                 Generation upto);
-
-            /** Evacuate object at @p *lhs_data to to-space, during collection phase
-             *  acting on generations g in [0 ,.., upto).
-             *  Need @p gc to pass to invoke AGCObject methods shallow_copy() and
-             *  forward_children()
-             *
-             *  Replace original with forwarding pointer to new location
-             **/
-            void forward_inplace_aux(obj<AGCObjectVisitor> gc,
-                                     AGCObject * lhs_iface,
-                                     void ** lhs_data,
-                                     Generation upto);
-
-            /** categorize fop {@p lhs_iface, @p lhs_data}
-             *  based on location of @p lhs_data.
-             *  Update @ref p_verify_stats_ based on the result:
-             *  increment exactly one of {n_from_, n_to_, n_ext_}
-             **/
-            void verify_aux(AGCObject * lhs_iface,
-                            void * lhs_data);
-
             /** Cleanup at the end of a gc cycle.
              *  Reset from-space
              *  (current from-space is former to-space,
@@ -252,6 +221,28 @@ namespace xo {
                                  AGCObject * iface,
                                  void * from_src);
 
+            /** Evacuate object at @p *lhs_data to to-space, during collection phase
+             *  acting on generations g in [0 ,.., upto).
+             *  Need @p gc to pass to invoke AGCObject methods shallow_copy() and
+             *  forward_children()
+             *
+             *  Replace original with forwarding pointer to new location
+             **/
+            void _forward_inplace_aux(obj<AGCObjectVisitor> gc,
+                                      AGCObject * lhs_iface,
+                                      void ** lhs_data,
+                                      Generation upto);
+
+            /** categorize fop {@p lhs_iface, @p lhs_data}
+             *  based on location of @p lhs_data.
+             *  Update @ref p_verify_stats_ based on the result:
+             *  increment exactly one of {n_from_, n_to_, n_ext_}
+             **/
+            void _verify_aux(AGCObject * lhs_iface,
+                             void * lhs_data);
+
+            friend class DGCObjectStoreVisitor;
+
         private:
             /** configuration for gc-aware object store **/
             GCObjectStoreConfig config_;
diff --git a/src/gc/DGCObjectStoreVisitor.cpp b/src/gc/DGCObjectStoreVisitor.cpp
index 9c2618d..713bf91 100644
--- a/src/gc/DGCObjectStoreVisitor.cpp
+++ b/src/gc/DGCObjectStoreVisitor.cpp
@@ -32,11 +32,11 @@ namespace xo {
         {
             switch (reason.code()) {
             case VisitReason::code::forward:
-                p_gco_store_->forward_inplace_aux
+                p_gco_store_->_forward_inplace_aux
                     (this->ref<AGCObjectVisitor>(), lhs_iface, lhs_data, upto_);
                 break;
             case VisitReason::code::verify:
-                p_gco_store_->verify_aux(lhs_iface, *lhs_data);
+                p_gco_store_->_verify_aux(lhs_iface, *lhs_data);
                 break;
             default:
                 assert(false);
diff --git a/src/gc/DX1Collector.cpp b/src/gc/DX1Collector.cpp
index d8f4021..6232bb3 100644
--- a/src/gc/DX1Collector.cpp
+++ b/src/gc/DX1Collector.cpp
@@ -587,19 +587,6 @@ namespace xo {
             }
         }
 
-        void
-        DX1Collector::visit_child(VisitReason reason,
-                                  AGCObject * lhs_iface,
-                                  void ** lhs_data)
-        {
-            // MAYBE: adapter distinct from DX1Collector that supports GCObjectVisitor facet,
-            //        calls DX1Collector::_verify_aux()
-
-            Generation upto = runstate_.gc_upto();
-
-            gco_store_.visit_child_aux(reason, lhs_iface, lhs_data, upto);
-        }
-
         auto
         DX1Collector::alloc(typeseq t, size_type z) noexcept -> value_type
         {
diff --git a/src/gc/GCObjectStore.cpp b/src/gc/GCObjectStore.cpp
index 18188a4..971d053 100644
--- a/src/gc/GCObjectStore.cpp
+++ b/src/gc/GCObjectStore.cpp
@@ -477,38 +477,10 @@ namespace xo {
         }
 
         void
-        GCObjectStore::visit_child_aux(VisitReason reason,
-                                       AGCObject * lhs_iface,
-                                       void ** lhs_data,
-                                       Generation upto)
-        {
-            switch (reason.code()) {
-            case VisitReason::code::forward:
-            {
-                DGCObjectStoreVisitor gcos_visitor(this, upto);
-                auto gcos_visitor_obj
-                    = obj<AGCObjectVisitor,DGCObjectStoreVisitor>(&gcos_visitor);
-
-                // called during collection phase
-                this->forward_inplace_aux
-                    (gcos_visitor_obj, lhs_iface, lhs_data, upto);
-                break;
-            }
-            case VisitReason::code::verify:
-                // called during verify_ok
-                this->verify_aux(lhs_iface, *lhs_data);
-                break;
-            default:
-                // should be unreachable
-                assert(false);
-            }
-        }
-
-        void
-        GCObjectStore::forward_inplace_aux(obj<AGCObjectVisitor> gc,
-                                           AGCObject * lhs_iface,
-                                           void ** lhs_data,
-                                           Generation upto)
+        GCObjectStore::_forward_inplace_aux(obj<AGCObjectVisitor> gc,
+                                            AGCObject * lhs_iface,
+                                            void ** lhs_data,
+                                            Generation upto)
         {
             // upto == runstate_.gc_upto()
 
@@ -693,7 +665,7 @@ namespace xo {
         } /*_forward_inplace_aux*/
 
         void
-        GCObjectStore::verify_aux(AGCObject * iface,
+        GCObjectStore::_verify_aux(AGCObject * iface,
                                   void * data)
         {
             scope log(XO_DEBUG(config_.debug_flag_));