Paypal groups

I need to modify my dolphin 6.1.4 groups functions
I want to add another function , when my members are creating a group
When creating a group, I want it to make it possible to make that group 'premium'and for anybody else to join, they will have to pay. This will be used for charities, and other stuff. For example, I had a friend that died last week, and I want to create a group,linked to his wifes paypal account. And when I will invite other to join that group, they will have to donate some money before they join. Once they join, they can use all group features, PLUS, there needs to be displayed a list of how much each member donated.