I had quite a shock when i saw state of my daughters dolls face it was coverd in green felt tip ! it was a new baby born doll she got for her birthday !
I did try to wash it off with soap , nail polish remover , bleech etc. no joy. what a mess.i did not fancy paying £30 for a new doll.
I was told about an acne cream ( panoxyl ) it has benzoyl and peroxide in it, the lady who told me said it worked on her daughters doll .Our baby born & annabell looked a mess and i had nothing to loose. so i bought some panoxyl off ebay .
i put the cream all over the dolls face and hand, keep the cream and doll well away from the children ! after a few hours when the cream had dryed all the green felt pen had gone ! it was worth a go.i used it on ethnic baby annabell too and the pen has now gone, she looks fab.
good luck hope it works for you !