Separate the overlaps
Place back hair behind the character and front hair above it. For a flattened image, outline the visible section and copy it into a masked layer. This separates existing pixels; it cannot invent the hair that was hidden by a hat.

Keep fine edges deliberate
Inspect hair over checker, white and dark. Soft edges and flyaway strands are not automatically defects. Use low feather values and compare before applying stronger edge repair. Keep protected colors if you want to preserve highlights while changing the main hue.
Export both pieces
Download each hair layer separately or include both in the asset ZIP. Choose compact PNGs for tight bounds, or shared-canvas output if you want to retain scene coordinates. Recheck placement manually in MiniMuse; the project manifest is not an official attachment protocol.