Membership plugin- How can use a custom Gravity form to pass user registrations to membership?

I have gravity forms managing my user registrations. I want to pass what the membership plugin needs via hidden fields from this form to the database. Please advise. I'm only testing locally at the moment so this is not live. But it strikes me as entirely possible. I can see that these two plugins conflict to some degree because the membership form which is supposed to dynamically show is not working (so I'm assuming it's because of a conflict and that it was activated after GF.) Any help would be appreciated.