Is model A & B both with no geometry checks? While trying to add model B to A through merge/inheritence(add body external reference) option fails due to type of reference skeleton setup. But when both A & B saved as step file and on merging the step files to new model C it works and gives a solid model. how to address the reference skeleton issue to directly merge the working part model B to A.
Answer: Usually this type of errors are based on models A&B being of different accuracy. Usually this type of errors are based on models A&B being of different accuracy. We would need to see the models to determine that.
If you make a new feature to replace round 9 with a completely new feature does the geom check still occur? I have found newer versions of Creo are less likely to create that self-intersecting check.
Answer: New features can sometimes use new algorithms and not have bad geometry.