Is this allowed and if so would I be an *ss?

I am traveling with 2 friends to Thailand. I am flying from ENA-ANC and meeting them in LAX then flying to SIN and on to BKK. We have premium economy tickets but it is a week out and figured I would bid on the SIN-BKK and the BKK-SIN business class since I have never flown business on SQ. Neither of my friends have ever flown business class and I figured if I got the upgrade I would let them take the seat for part of the time if the airline allowed. My friends aren't hooligans and would be respectful of the situation.

Also on a separate note, can we or should we link our reservations? My ticket is from ANC-BKK where theirs is LAX-BKK.

Thanks