Example code for copying a field from an unbound table to a form's bound table

I added UD field “LineComment_c” to the TFOrderDtl and TFShipDtl tables to hold line specific comments.

I added all the UI elements and bound them to their respective tables.

I want to add a button (in the Trans Order Shipment form) that when clicked, will copy TFOrdDtl.LineComment_c to TFShipDtl.LineComment_c, when

TFShipDtl.OrdNum = TFOrdDtl.OrdNum && TFShipDtl.OrdLine = TFOrdDtl.OrdLine 

What is the basic C# code for retrieving TFOrdDtl.LineComment_c, given TFShipDtl.OrdNum and TFShipDtl.OrdLine?

Should I set TFOrdDtl.LineComment_c by referencing the GUI object, or via the adapter?

Were you able to solve this? Looking to do something similar.