What is best way to add more themes for free users?

OK so I am using Pro Sites and I have a free account and am offering a paid pro package. With the Pro package they get 150+ themes to choose from. I want to add a few more themes for the Free account people. What is the best way to do this? Just simply Network Activate those specific themes? I tried just doing that but went back and logged in as a free user to test it and they are not offered. Still says it is a Pro Package Theme. What am I missing? Thanks