unreal 4 – How do you import submeshes on a skeletal mesh?

I’m trying to help out a friend on an Unreal issue. He has a Unity scene he’s trying to convert to run on Unreal, and getting the models right has been a bit of a bumpy road.

Like many models, this has several sub-meshes on it. Some of them are mutually exclusive and should only have one out of a group of submeshes turned on at once, so that the same basic model can be repurposed as multiple different characters with different base geometry. In Unity, this “just works.” Import the FBX file and you get a prefab with all of the submeshes as sub-objects, and everyone’s happy.

In Unreal, it’s a bit more complicated. A bit of searching came up with this question from 4 years ago, which is exactly the problem I’m having here, and says exactly how to deal with it: unselect the “Combine Meshes” option in the importer. Except that this model is rigged, and for whatever reason, when you check the “Skeletal Mesh” option in the importer, the Combine Meshes option vanishes and everything gets lumped together in one single blob of mutually exclusive geometry!

I find it difficult to believe this this would work perfectly right out of the box in Unity, while Unreal, which has been around almost a decade longer, has no support at all for such a fundamentally important operation. But at least at first glance, that appears to be the case. Are there any more experienced Unreal devs out there who know how to get sub-meshes to import correctly on a skeletal mesh?