Ok I might be pushing my luck but I am going to describe the feature I am working on and see if anybody has ideas on if its possible. 

I have a form called credit memo. This form has a look up field to the Vendors form. The Credit Memo form has a subform that allows the user to choose products that are being returned for a credit memo. There is a field in the main form that totals the subform and gives a total credit memo. 

I also have a form called Quotes. This form also has a lookup field to the Vendors form. What I am trying to create is when the purchaser creates a new quote he chooses the Vendor in the form. I want to then have the system calculate the total value of open Credit Memos for that Vendor and put it into a field that I have for discounts. I actually think I can do this part fairly easily but still looking for advice and examples. I am not a coder but I play one in the office. 

The tricky part that I am not sure is possible is to then have the system go thru the individual Credit Memos and change the status of each until the total has been reached. Let me provide an example to explain better. 

Company A has 4 open credit memos each individually totalling $50 to have a grand total of $200 worth of credit memos. The purchaser creates a new quote and chooses Company A at this point the system puts the $200 into the Credit field of the form. (Help with this would be great) The purchaser uses the subform and creates a total quote for $150. (Here is where we get tricky if at all possible) Once the Quote is approved. (Decision box) I would love the system to automatically go thru all the individual Credit Memos and change their status (Drop down field). The extra tricky thing is that if in the above situation there is not enough new purchase to cover the whole credit the last credit would not have its status changed. 

I realize this is pretty sophisticated but I think it would be an amazing feature if it is at all possible. Any help or knowledge in this realm would be so greatly appreciated.