RMA Does Not Have Sales Order Attached To It

Hello,

I am using Sage 100. I received an RMA about month ago and the Sales Order I thought was attached to it was either deleted or used by someone else. I wrote the SO # that was created in the "Generate Transactions" screen when initially receiving the RMA. 

There as no cross-ship required or Xpress Order. How do I attached my free floating RMNA to a nice anchored SO? 

EDIT: I did search though the Sales Order list (F2)