[Paid Memberships] Request Additional Information When Signing Up for a Membership?

[CrusaFiction]

Hi,

I am looking for a way to request additional information when signing up for Paid Memberships on my site.

I am looking for this information to either be added onto the PayPal transaction (like special instructions/extra info would be), or to be added to the users account profile and made visible only to admins/moderators.

Does something like this exist, and/or is this concept possible?

Example:

User A signs up for Paid Membership A. Paid Membership A requires you to include your Video Game Username DURING (Preferably before) initial Payment. User A enters his information in, and then continues to pay. If User fails to enter information (no info given), then Payment will not continue.

Reason behind it:

I host a Membership area for a Video Game server, and we for the sake of making sure we know which members in our server are the proper members on our website, would like them to have to put their username information in during their purchase. We already have it set to request Account/Username info during registration, but sometimes some of the memberships only alter ONE character on the users account, and we would like to be able to know which one specifically they are paying for.

Does something like this already exist/is this possible? The only Payment method we accept is PayPal.

Greatly appreciated