Create a secondary calculation in a repeating subform based on a drop-down list?

Hi all,

I need a crazy bit of scripting. Not sure it's even possible.

          What I have:

1. repeating subform SummarySub with dollar amount
   1. calculation field at end of form TotalOver gives total dollar amount from all iterations of SummarySub
      
      so far, so simple. but then:
2. I need another, repeating subform SubRow at the end of the form to give another total:
   1. based on Payer Name drop-down list in SummarySub
   2. and break out totals from all iterations of SummarySub based on payer names as chosen by the user.

Ideally, the subform (B) (Payer Totals) at the end of the form would add instances as the user exits the Payer Name field. I haven't been able to figure out how to do that and keep the value in the (Payer Name) field of the added instance.

Does any of this make sense?

I'll appreciate any help.  I'm trying to learn more about JavaScript in LC, but my deadlines just keep coming....

Many thanks

Laura

Dropbox - AFBS_OverpaymentReport_121914.pdf