Numbers - linking pop-ups "v look-up" in a formula, simple addition

I have created a pop-up, using the tool to acurately designate a category for my daughters budget. I am trying to build a spreadsheet that is completely automated. her role is to enter the number select the category. I need to have the ability to link the category at a summary level and have the worksheet identify the category and add numbers which would be linked to the category. Any way of using pop ups in a simple addition/sum formula?