Filter portal duplicates

Hi all,

I have a question where I can't seem to find a proper solution.

I have my fields: product item, quantity quoted, quantity worked.

Now these product items can be selected by the employee on a per project basis.

This works fine, however where there are multiple of the same product item and I link it to the selected item number, the quantity quoted will be correct, but the quantity worked will be the same number per line item.

I hope this is not to confusing. So what I want to do is the following:

- if a product item already exists in the portal (duplicate of the same item within that project), I would like to display the sum of the quantity.

So instead of displaying:

Item 10.0.4.5 - quantity : 4

Item 10.0.4.5 - quantity : 5

It should display:

Item 10.0.4.5 - quantity : 9