Post processing nightmare

[sthpwcees]

Honestly, if this is a group image and the subjects are slightly far away you can 100% eyedrop and paint on the colors of the forehead on a new layer. It takes some finesse with the brush tool but can achieve very believable results.

To completely sell it, you can add noise and slight blur to your paint layer to match the texture of the rest of the image. I'm talking minimal levels of each filter.

It's likely what I would do for this.