Project Invoice Grouping for Prepayment

Summary:

Prepay from Customer

Content (please ensure you mask any confidential information):

We have implemented this new feature in Contract ( prepayment from customer) where we raise advance from customer invoice and Prepayment Application on Progressive invoice)

But in Saudi Arabia there is a govt. Portal called ZATCA ( Zakat, Tax and Customs Authority in Saudi Arabia) that doesnt accept Negative Line.

When we tried to group Invoice Lines it is not grouping the lines as shown in the Screen shot .. It should group the lines and show the total ..

Please suggest

Thanks

Version (include the version you are using, if applicable):