I usually make a trans map of the brows, that can be used and color applied in the Diffuse Color node.
This is what you call a "mask" isn't it?

BTW: The trans-map also will act as a bump map if you need it to.

When I make eyebrows right on the UV map, I make a matching trans map.
Just apply it as a transparency and the eyebrows on the face map will show without any annoying lines.

This way there is no need to remove the eyebrow mesh.

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