How to create a new field with Yes or No

[#1]

I'm looking to add my own field to two separate files to know if payment received. one file includes received payments and other includes outstanding payments. I want to create a new field in the received that says 'Yes' and a new field in the outstanding file that says 'No' and then combine the two files

[m_woolf]

When you read the "Received" file:

'Yes' as NewFieldName

When you read the "Outstanding" file"

'No' as NewFieldName