U can try contact them personally to file this issue to transfer, because u can't do it via manage my booking.

Or else, you have to purchase another baggage allowance under your name, and just burn the original one because u can't refund once its purchased.

the last time i ask airasia was that, the total weight is shared if you are under the same booking no.

yes

for AA you can...
however for MAS you can't

Nope

Remember to ask refund for the Airport Tax paid