Adding Multiple Items to Cart

Hello there

I have a bit of a unique situation;

I am building a clothing site where the user selects type/style/colour then these parameters are passed through to the size selection page - all fine.
What I want to do is to return the contents of my sizes table (it is dynamically built through the backend) - S,M,L etc and put the results in a normal repeating region - again, all OK so far.
In the repeating region I then put a 'quantity' box against each size (default 0) for the user to complete and then add the lot (including the quantity) to the cart.
Also in the repeating region (inside the form) are hidden fields which hold the parameters already passed (same for all garments)
I followed the instructions for eCart v3 but this doesn't appear to work properly at all - it returns the last record quantity for all rows in the cart.
I don't need the checkbox filter, as I will only be passing the rows where the quantity is positive.
Is this possible?

Thanks