Greetings - I'm trying to find a field in the LN tables and so far I'm not finding it.
Can anyone offer any suggestions?

When using the session:Match/Approve Purchase Invoices (tfacp2107s000)
to Approve approve and Invoice that my have some Additional Costs included.

I'm trying to find if the User who actually performs the "Approve Invoice" is recorded along with the transaction.

I've been asked to add a column to an existing report (tfacp1431m000:Print Matched and Approved Purchase Invoices with Receipts) which will show the User Id that approved the Invoice...but so far all I find in the User who Authorized or last modified the invoice....

Is this recorded in the LN Tables somewhere?

You will need to go to the approval document, so use tfacp200.tapr and tfacp200.dapr and find in tfgld018 the document number, the field tfgld018.user will be the user who created the approval document and is therefore also the "approver".
Regards,
Michiel

This information you can get from approval document no.
you have to develop this in Infor.