varnishing over mixed media canvas - help please!

Hey! New to the forum and need a little advice if anyone would be kind enough to assist...
I recently finished a commission of acrylic and watercolour base (not my usual painting style, I was asked to paint a character from a children's book (ugh) and to use watercolour - which I hate, so I cheated and used some watercolour in the background, then pastel coloured acrylics for the character itself!) The character has a thick black outline so I have used an ink fineliner to achieve this, but when painting acrylic over parts of the ink, it showed through with a vengeance! I had to use 10 or 11 coats to cover small parts of the ink when I painted the character in the foreground. This ink is a nightmare. Now it is completed (and looks OK I think) I want to varnish over it, but I'm worried that the varnish will cause the ink to seep or spread or totally ruin the painting in some other way. Does anyone know if there is a varnish that will work over acrylic, watercolour and ink? (particularly the bloody ink!) Or should I not risk it. I'd be pretty p*ssed if I slapped varnish over it and the damn ink ruined everything. Help please! Thanks in advance. Jacey