I have set up Wix Paid Plans to allow membership sign up and recurring payments but I would like to embed a form as part of the sign up so I can collect additional member info and have a terms and conditions, disclaimer acceptance etc.
Also, being able to have multiple payments for one plan would be useful e.g. one off registration/joining fee/deposit then monthly/recurring fee.
Pro rata amounts would also be useful as we prefer to have everyone billed on 1st of the month so if someone signed up part way through the month the system would work out the pro rata amount for remainder of current month and then take full month payment on 1st of next month.
Under booking services being able to set a number of sessions for services rather than just unlimited would be great! We have memberships which allow 2 free Personal Training session included in the monthly fee.
Would be good to have the option to auto create invoices for each monthly payment (similar to how this is done for store orders)
Would also like to see the plan details and terms that member has signed up to under the contact name in the Wix dashboard. (We like a PDF copy of the agreement/contract etc) Currently we do this separately in person when they come to the gym but I hate paper lol 
Apologies, I know its a lot and this is a relatively new feature (I am also very new to the Wix platform) but excited to see what else comes from the Paid Plans feature.