I am using Windchill PDMLink Release 12.0 and Datecode with CPS 12.0.2.11
Relations constraints for Satisfy Trace link and Allocate Trace link are not inherited by the subtypes of the Parent Type as described in documentation.
The TraceLinkConstraintsHelper.getRelationshipConstraintsData method called in $WT_HOME/codebase/netmarkets/jsp/traces/traceLinks/addTracLinks.jsp uses AssociationConstraintHelper.service.getAssociationConstraints(paramTypeIdentifier).
Work around is to create relationship constraint for subtypes, but that is not ideal.