You cannot prescribe meshes that are compatible between part instances. If you require mesh compatibility between two or more instances, you can do one of the following:
Create a single part that contains all the bodies so that multiple instances are not necessary.
Assemble instances of the parts in the Assembly module and use the Merge/Cut tool to merge the instances into a single instance. If you need to maintain the concept of separate part instances, you can create a partition at the common interface of the merged instances.
Similarly, you can create a single part instance from a group of orphan mesh part instances, using the Merge/Cut tool to merge duplicate nodes. For more information, see “Merging and cutting part instances,” Section 13.6.
If you must use separate parts, you can use tied contact to avoid the issue of mesh compatibility. Keep in mind that this is not true compatibility, and the accuracy of the solution may suffer. For more information on tied contact, see “Understanding interactions,” Section 15.3.