What can I use to make fake drinks?!
Answers:
If she hasn't actually had any alcohol in the past, you could try adding tonic water. It has a bitter, "foreign" taste that she might assume is the taste of alcohol, provided that she has no experience with the latter.
If she has actually tasted alcoholic drinks before, she might be hard to fool, since alcohol produces a distinctive warm, burning sensation and vapors that tend to give it away in all but the tiniest proportions.
try adding a little bit of club soda or seltzer to make it lightly carbonated. that helps hide the fact there is no alcohol. not too much so it doesn't taste like grape soda.
just buy sparkling grapejuice