Can someone please help confirm whether this process I'm thinking of can work?

I have Travelbank funds I want to purchase for my friend for UA codeshare (Air Canada metal) flight. I plan on buying a regular economy ticket in the friend's name, and cancel after 24 hrs. I presume then my friend will be issued a future flight credit. I then use the future flight credit to purchase the UA codeshare flight (since i understand that FFC can be used for codeshare).

Does this sound right?

Bonus question: does the same apply to child ticket?

TIA