I have a bit of an issue creating a rule to sort received email and its reply into 2 different folders and its confusing the hell out of me

I receive emails containing client expenses from staff member and want to have them all in a sub folder of the inbox titled 'submitted expenses' - that parts easy

The expense are then approved and emailed to the finance department. I want the sent email, containing the approved form, to be moved to a sub folder of the sent items titled "approved expenses"

I have tried quite a few different ways but it either moves everything to the sent folder, or to the inbox folder, or doesnt move anything at all. Im sure its some stupid little thing Im not doing but its driving me crazy