Formula for pop menu in numbers.

im trying to add a formula to a pop menu option for. budget my wife and I are doing. ill try and explain it as best as I can but basically the "Which Paycheck" column in table 1 has a pop menu in each cell that will allow me to chose which paycheck that item is coming out of but I want the amount from the table 2 columns to go down as we enter which paycheck each item will be designated too I know there are apps for this and that I can just download it but I really want to get better at doing it myself and I want to learn numbers. so basically as an example, the first thing would be sam tithe. we would want to take that out of paycheck S2 so the $350 would be taken out of S2 for Sam missions we would want to take that out of S1 so it would be $225 removed from the amount in S1 and so on and so on.