I would also like to know this answer. We have an invoice that was entered and paid through AP, but it should have been entered and paid through PO. *following

Adjust / reverse the AP invoice and re-enter it properly through PO Receipt of Invoice Entry.  There is no easier way.  An invoice entered through AP cannot be linked to any data in the PO module, period.

After you reverse the AP invoice, it should have a negative balance (since it was already paid)... then use a zero $ manual payment to offset that negative balance with the properly entered PO invoice.

Can you reverse an invoice that has been paid?

Technically you don't "reverse" the invoice, post an adjustment (entering the original lines, as negative), which should be possible as long as it hasn't been purged from the AP_OpenInvoice file.

https://help-sage100.na.sage.com/2022/index.htm#cshid=45001&chm=AP

Try it in a test company first if you're unsure.

Doing it now. Thank you! Than pay with a manual payment/wire transfer?

Actually, I now have a credit and debit. So now I need to clear them 

https://help-sage100.na.sage.com/2022/index.htm#cshid=45002&chm=AP

Thank you so much!

In the bottom right corner of all data entry / maintenance screens, click the "?" button for quick access to the help files, which are the links I posted.