Texture editing question

[SauronMelkor1234]

I've edited a bunch of texture files for this and other games and have pretty much got the hang of it, but there's one issue I run into occasionally and just can't figure out how to fix, hoping someone here can let me know what I'm missing. Specifically, if I make a change that exposes skin (like changing a neck or hem line), the skin becomes a blank white texture. I generally try grabbing some of the skin texture from the arms or other parts of the file and then end up with just a blank white area rather than the npc's skintone (see attached image, the white area should be skin). This hasn't normally been a big deal as I could always paint in the skin tone if I needed to, but in this case, it affects the entire crew, so there is no one skin tone that would apply to all. Would appreciate any help you can provide in steering me to where I'm going wrong here, because its getting pretty annoying to do trial and error and I've not been able to find any posts or documentation that relates to this issue specifically. For reference, this is in LE3 and the texture I'm currently trying to update is HMF_ARM_CTHb_Nav_Diff_Stack.

 

Thanks.