If I book a QR J online during one of their promos, can I go to a TA and have them add a domestic AA Y leg from my city to the QR gateway as separate tickets but on the same PNR? Same way, can a TA add another leg on a third OW carrier from the QR final destination to another intra-asia destination on the same PNR that QR gave me? I wonder if a TA will be able to do it. Just to be clear, I'll be happy to compensate the TA (or the airline) for their services if they can do this. I just don't want to lug around my luggage in the airports, and go through passport control or visas just for the connection in a foreign country. I Thanks for any insights the experts can provide.

EDIT: If I want to combine a regular QR fare (I can see the fare basis on ITA) with a domestic AA leg in the UA, or an intra-asia UL leg, can a TA combine them in the same PNR? If the fare basis allows end-on-end connections, this should make the ticket price astronomical right?