PCPA is looking for a moodle plugin / extension which allows users to "upgrade" from one user account to the next. ie the user has already paid for an account via PayPal. They then see another account (better course which you provide) which they would like to "upgrade to".
As the system sees it, the user has already paid X amount (for their initial subscription) and should pay Y amount for the addition of the new account because it gives a certain added benefit. However, how the site admin and user sees it, is that the user has already paid for one course X and they want to improve their subscription to for X-Y=Z.
For a new user to subscribe to Y would cost them 100 credits which is 100%. However, as the previously subscribed user has already paid for a previous course, they should only be liable to pay 20% for the new upgrade for the course as they have already had a "taster".
The plugin / extension would allow users to transition between roles as student in one course and another for a price which is based on a percentage of the price that they paid to subscribe to the initial subscription.
The module would have the following options for admin:
1. Which course the user has the ability to upgrade to.
2. The percentage of the initial cost of subscription it costs to transition from one to another.
To be involved go to: http://pharmacycpa.com/mod/resource/view.php?id=552