Customer MUSTS

I am creating a site for my fundraising business. When a customer initially registers with my site I need for them to chose from a list of pre-registered sports teams so that a percent of their purchase will go to the correct team. I'm looking for suggestions on the easiest way to set this up. It needs to be a must setting in that it will not let them continue on to purchase unless they choose from the list.
Thanks!

Just to clarify....

Is this a once only choice on sign up.
ie: Once you make it, its stored and that's it.

or is this a choice that can be made and changed per purchase
ie: The customer can choose the team during checkout
And they can support a different team at different times for separate purchases.

Or is it a choice that is persistent, but can be changed in the customer's account page?

Well my thought was originally the first option but after reading your post I believe I need the second one....where they can choose a different team with each purchase because some parents and grandparents have kids on several different teams and totally different sports depending on season.... But I still need it to be a obvious field they must choose from.

Given this situation, I think a choice at checkout would be most flexible and appropriate. How many teams will there be to choose from? If not hundreds (making the choice cumbersome) it seems like choosing at each purchase would have a decent customer flow.

If all goes well there will be hundreds :) that's more business for me! As long as its a drop list in alphabetical order with city name being first then team name it shouldn't be a problem.
So now the big question....how do I code it so that they MUST choose to submit sale?
I plan to include a no team option in the list for retail sales from people just shopping but the buyer needs to be forced into making that option for non team sale or specific team sale.

Where did everybody go?? :(

Still need help here! Is there add-on or can it be done with normal setup? Need to have this thing up and running by Aug 2nd .... HELP!!!:ohmy:

You're asking for somthing that would have to be custom-coded to your specific needs. If you aren't able to do it yourself, you'll most likely have to pay someone.

I found several threads (searching for donation and charity) where much the same question was asked, and none had any useful replies. Melanie did suggest that some tweaking of this mod http://www.zen-cart.com/downloads.php?do=file&id=704 might let you do something like that.

Ok I thought it would be a edit in checkout ...just add or edit a field. It doesn't have to have any purpose except printing or showing up on the invoice ... Not like keeping track of reward points or anything ... That will all be tracked elsewhere. It just has to be a mandatory field.

This seems to add a field on the checkout shipping page, but not a dropdown with the recipients listed. You might be able to do something with it.

http://www.zen-cart.com/downloads.php?do=file&id=1678

Ok I just had another idea....want to run it past you guys to see if you think it would work...
what if I added a attribute to each item that would be a drop list with the teams so they could pick what team the money goes to for each item? Again, was thinking about a Mom or Grandma with kids on multiple teams. Let's say they want to buy a Build A Bracelet to wear to support two different kids on two different teams. They could make the purchases all in one sale instead of checking out, paying and having to start over. They could make one bracelet with one team colors and kids number and on that page where they customize it, they would choose what team, then add to cart, make another bracelet of another color and number and chose a different team...THEN checkout and pay for both and the invoice would show details for both....right?
I, on the other hand, would be adding the team names as they register just like I would any attribute value....we can add to attributes as often as need be, right?
Will this work like I think it will?
Thanks!

Sounds like it should work. My inclination would be to set up a test Zencart site (a good idea, anyway) and try it there first.