Originally Posted by
ydobon
I don't think you can use your UA Travel Funds for an itinerary that includes no UA metal: "funds can only be used to book United-operated or United Express-operated flights, plus certain subscription products."
You can but it takes an extra step. First book an all UA itin using the desired TB funds. Then either change to the preferred itin with partner flight or cancel after 24 hours and get an FFC, which then cancel be used to book at partner flight. I prefer the second approach as change flight can be wonky, but either way can work fine.