problem with multiple mesh/multiple uvs characters

The mistery anyway is that, when the meshes are imported in unity separately and parenetd to the body bones, the textures show up, all of them: when imported in one mesh from mixamo, just the textures of one part (usually the body) are visibile after assigned to materials. 

First off thanks. As for the "horseman" part: I rigged just the body (foot/legs/torso: no head. I substituted the head with kinda cone, which is transparent), then imported it in Unity, added the head (an helmet, parented to the uppermost head bone of the rig), then an harness (to torso) and a belt (to hip) with holster with string modeled around the right leg. When I start the simulation play, the body walks correctly, but the items act weird (the helmet stands firm but sinks into the shoulders for a bit: the haerness sinks into the body, the belt looks ok alittle, but the leg string is stiff and goes outside from the leg). I was forced to rig just the body and layer all other parts in Unity because, when I tried to upload as a ensemble, it happened that some parts displayed no textures once imported in Unity: and I was unable to have them showing up. And it was not always the same parts: they changed. Sometimes the body, other times the accessories. The problem didn't surfaced when the parts was imported one by one ad layered upon the rigged: but I faced the above problems though.   

All the parts was modeled/uvmapped in Modo (and are multi-material) and textured with Photoshop/Quixel. Perhaps the problem is inbetween Modo/Photoshop? But I don't know what to search for: the textures seem all the same as format, and a thoroughly scan of the material trees ascertained (at least I guess) that the materials are all the same as for details. I'm going crazy.