How To Create Multiple Links In A Form

I have a form that tracks the budget. It is a small budget. But my problem deals with req. dates and req. amounts. You will see from the example I gave you that I can input one req. date and one req.amount and my calculations shows the ending balance. But how do I make fields where the same person can buy from different vendors in one day? I want to be able to show the date and the different requisitions and have the calculation subtract from each one, thus showing the ending balance. Hope this makes since. I attached the file of the example.

So under:
Date Req. I need to be able to put mulitple dates
Amount Spent: Different amounts that correspond to the date.
Ending balance: The ending balance will be correct when all of it is done.