Hello and thanks guys...
Marc, I always paint the figure by pices when the figure ask for it, I have the same problem than you, but I use acrylics, I attached the pice and also I use some putty then I go back with my mixture base color and paint the area where the putty is, after that lights and shadows again. I always use a pice of papper where I write all my mixtures in case I forget some mix colors...
hope this helps
ER