Would like to make one from a mix, Should I use fv mix, fv pudding and fv creamer as the liquid or white mix, fv pudding and fv creamer?
Cakes mixes can stand up to a lot of "doctoring" but even they have a limit....
Adding pudding and liquid coffee creamer will probably cause your cake layers to sink upon cooling (too much sugar):
Also, French vanilla is not a type of vanilla. It is a term used to describe an egg-custard base for ice cream. So adding extra vanilla extract would increase the vanilla taste without causing your cake layers to sink.
Here's a recipe that uses any flavor cake mix and instant pudding mix: