Need Prosites Advice on proper theme setup

OK I just need some guidance beyond the user help text.

When I network enable all my themes, then nothing is available in prosites to assign to a membership level. If i leave them all disabled, they're all available to assign, but in an account I only see the themes that have been assigned to my level.

What I'd like is for the themes and plugins available to higher levels to be seen and for a button to say "want this, upgrade" or some such wording, just like in edublogs (yes, I've studied it, it's fab lol).

SO, the query is, how do I accomplish this? What am I missing?