Importing UV & materials

This may be more of a blender question but the end result has to be compatible with unreal so,

I have a complex character in blender when UV unwrapped won't fit in the UVmap for high res texturing to look good

Now what method should I use that works with unreal to get higher quality textures/uv?

The only option I can find are more material slots since each material slot imported has it's own UV without overlap which does work but I would like to have as few slots as possible since the slots would use the same exact material anyway

In blender there are multiple UV maps but importing these to ue does nothing, whats the normal method for this? Am I doing something wrong?