Shabbat help

Question

This coming Shabbat there is a rabbi giving a shiur. I want to attend the shiur but I don't want to leave my wife alone with the 4 kids. So I want to hire a teenage girl to help out. But then I would be paying her to work on Shabbat. What do you suggest to make it permissible? Can I have her work for five minutes after havdalah and say I am paying her for this (when everyone knows I am not)?