How do I charge for the number of spaces?

I am booking sellers at an event, not attendees, so my registrants book spaces - tables actually. The cost depends on how many tables they reserve, not how many registrants are at the tables. For each table, they are allowed up to two free registrants but not everybody uses the maximum.
For instance one person might reserve 3 tables just for himself, another will reserve 3 tables with 6 people attending, the cost should be the same.
I've created a custom field what will adjust the charge for the number of tables but I also need to know the registrants names to send out passes to allow them in at set-up. The group registration process will collect this information but how do I get it to not charge for the extra registrants? Setting the group rate to $0 doesn't seem to work. If I could find a way to get it to calculate the number of free registrants based on the number of tables, then either block or charge a fee for any extras that would be awesome but my php skills are basic at best and working out all the possible combinations of group rates makes the form too complicated.
Has anybody else done this? Can you give me some ideas or point to a site that does something similar. I'd greatly appreciate it and will post my solution once it's done.

I'll now make my question more specific as I'm still working on a solution. I tried editing the file com_eventbooking/views/register/view.html.php. I changed line 596 from "$totalAmount = $rate*$numberRegistrants + $extraFee ;" to read "$totalAmount = $rate + $extraFee ;" but it had no effect. I'm obviously missing something. Anybody know what?

Hi

I read your description here but still don't understand what you want . Maybe it will be good if we have a quick chat so that you can explain the problem you are having and I can give you a solution ? You can contact me via Skype, YM, MSN or Gtalk, the contact information can be found at joomdonation.com/index.php?option=com_co...ntact&id=1&Itemid=18

Regards,

Tuan

Thanks Tuan - that's great service.

I have signed up for gTalk and will try to contact you that way. I am in the Eastern Time Zone.

Lorne

I am from Vietnam, GMT + 07 . I am usually available from 8:30am until 11:30pm, so feel free to talk to me when you are available.

Regards,

Tuan

Hi Tuan - I sent out an invitation to you through gMail but need you to accept before I can call.

Lorne