I figured it out:  
 
AR-C: Enter negative check $ amount.  A pop-up came up to choose 'NSF Check' or 'Reversal' - I chose reversal.  The system entered the correct credit $ amount and put all the invoices back into A/R.  
 
AR-M:  Because I wanted to pay invoices that were dated after the payment, I then entered the payment as customer deposit.
 
AR-C:  Entered $0 dollar payment to pick invoices to pay with credit that was created from 1st AR-C transaction above.

Correct, and to take it one step further, if you have a single check that paid invoices from multiple customers, you need to reverse (as needed) each customer's payment as a separate "piece"