There is a very good chance it won't work out the way you'd hoped.
GF is all I do and I have found over many years of baking that never works well.
Gf isn't as forgiving as reg mix. It doesn't take kindly to adding extra wet ingredients. You can try it but don't be surprised if it doesn't work. I've never had success with it.
Best bet is to use a recipe meant to be made GF. And as a side note the box mixes are not great at all.