Model Import issues

I’ve been importing some models and have run into more issues, so I download a pack of hats and they came with static mesh pieces for each hat, if I try to combine meshes it combines them all into one mesh instead of the individual hats, so I put them in UE and merged all the related meshes and then brought them back to UEFN and now when I try to plug them into Niagra (I have niagra mesh enabled on material) they don’t show up in game, but if I test with mobile the mobile account can see the mesh on my main character, not sure what’s causing this tried messing with LOD render distance and detail but it doesn’t work still, and I’ve done this with a bunch of other models and it works completely fine but this pack that needs the meshes put together I can’t seem to figure out, what am I doing wrong?