Close, but no. Vertexs have their own normal system, called vector normals. This is the points on the object telling the polygon which direction they should go. It doesn’t change the shape of the mesh, but it will change the look of the edge of the model, making two separate objects look like a single object when placed together. No texture maps required. It’s all in the model. Example; In Maya, when you smooth an object, you’re changing the vector normals to represent a smooth object. When you use the Set To Face normal tool, the Vector normals are told to stand straight out, giving you that low-poly, segmented look. These are Vector Normals at work.
Now, in Maya, you can easily copy the vector normals of your complete body onto separated parts by using the Transfer Attributes tool. Make sure to open the options and double check that Vector Normals are selected to transfer. (I am unaware of how to do this in other software, but there are probably semi-easy ways to do it.) Once you’ve exported the file and imported it into Unreal, you shouldn’t see any seams.
Below is one of my models that have been cut up, but the vector normals were copied from the complete model, so when the models are together, they appear as a single model. Note: On the bottom image, body-changing blends are applied, which is what is causing the seams to appear. This is why I was saying don’t cut along areas that are being morphed. When/If Blend Normals are added to Unreal, this issue will disappear.
