Adding quantity field for the same material number in Table control

Hello Experts,

I have an requirement, where I need to add the quantity field when the material number is repeated in a table control.

Here I show the pop-up message "Material already exists, do you want to add the quantity". If the user clicks on Yes I need to add the quantity.

I created the pop-up message using the FM " POPUP_TO_CONFIRM" and tried to add the quantity filed using COLLECT statement but I couldn't because my non-numeric field value will be different and it will insert new entry with same material in my internal table.

I have a z data base table & internal table with the below fields in it.

Best Regards,

Mani