Looking for some information on how I might accomplish a specific scenario for CBSubs:

1) User is presented with registration form and must choose one top-Level CBSubs plan only.

2) Automatically assign one child plan based on province/state in the form when submitted: i.e. One child plan per Canadian province; if they're from Ontario and choose the Top-Level 'Regular' plan the sub-plan would automatically be the 'Ontario' plan underneath it (Regular Member -> Ontario) without having to show all these plans (thus allowing them to select one that's inappropriate which we can't have).

3) After the initial plan they still need to be able to purchase additional sub-plans in different provinces if they decide, but the initial one has to be from their home province.


So my question is, how do I do this and where would I start? Will it require writing my own plug-in to CBSubs and if so where is the documentation for doing that?

Thanks!