Adding additional sprites to character

I have an animated character. Thing is, I need to add an extra layers on him - they will become visible only in certain light conditions. One of extra "light" layers is on the face and other on the coat. I presumed there will be no problem, if I put the extra sprite as a child to already animated object, but apparently this is not how it works.
Any ways to do that now? Aunt Google spews out totally different stuff to all my questions