Adding Layer into Deformer

[lament marlin]

Soo I realized the back of my hair wasnt included in my HeadZ Deformer (so like when I tilt my head left my back hair doesnt follow) can i apply it now even though its been set already? and can I do it without moving the position of my layering?

[fluid rapids]

in the "deformer" window, you can drag the back hair art mesh into the deformer