How to assign a user to a shopper group ?/ Urgent _VM2

[lazou]

Dear members

I really need  help for this matter:
I use VM2 and create different shopper groups according wether thet benefit from particular prices or not. Each client have to sen a form with information, so once formare received, I could assign (for the moment manually, but automatically could be great too) them right to specific shopper groups.
However I noticed I could not manage the right befor they filled their order... But this is nonsene! this mea, I would have to wait for them to order (at general price) to tehn grant then pspecific price?
How can I simply manage theuir rights without having to fill all these information?
I tried to use mapping with RSform pro (to mapp account information with virtuemart user nfo) but this doesn't work. May be I did it wrong?  (RSform answered that they couldn't help me with Virtuemart...)
I know that in VM1 you could change php code in ps_shopper.php . However this file doesn't exist in VM2...
I really don't know how to proceed. I'm a  beginner with php and joomla. Please could you help me ?  A quick answer could be really appreciate !  (excuse my english) Many many many thanks in advance!!!!