Prepare allied shipment quotes for larger alliances

docs/ALLIED_TRANSIT_RULES.md

@@ -136,6 +136,15 @@ optional arrival compositions are not expanded by the Basic prototype.
 Advanced ordinary physical entry is connected in the follow-up above.
 Refinement of interrupted and mixed-cohort interactions remains later work.
 
+The unexposed three-member alliance foundation can quote a receipt with
+multiple allied witnesses against one physical baseline. It checks current
+allied occupants at turn end, including an ally who arrived after the shipment;
+this online interpretation remains provisional. The native engine currently
+uses the shared receipt and quote only for the existing reciprocal pair.
+Group entry, turn-end handling, controls and remaining alliance effects must
+be connected before three-member play is offered. The unlimited-size alliance
+variant requires separate work beyond the present three-member cap.
+
 **Brief smoke evidence:** paid Basic allied arrival followed by Medium's
 native departure and clean ending; ending without departure removes two
 new visitors while preserving five old counters and the ally's three;