My brother bought three tickets to Brazil: one for him, one for me, and one for my husband. He bought these tickets while I was pregnant, with the intention of letting us use his tickets for our infant, since we didn't have a name or birthday, yet. Now, I'm worried the airline will no-show him and not let us have the seat for our daughter.
Should I call the airline and ask them how to proceed, or just hope for the best?
What you need to do is get a refund for the unused tick and buy an infant ticket. An agent of the airline can help you do this. Adult and infant tickets are not the same, so you cannot easily change the name or passenger info as is possible when swapping adult passengers.
Technically you can do one without the other. Should you be willing to fly with the infant in lap, you can most likely get an infant ticket even if the flight is full and those are very cheap. Otherwise, there must be space left which is why getting your brother's ticket cancelled might be needed.
In any case, unless you paid for refundable tickets, there will be fees for cancelling the ticket and for buying the infant one.
As mentioned above, adult and infant tickets are not the same. But also, tickets are generally non-transferable: the ticket in the name of your brother is for your brother, and your brother only. It cannot be transferred to someone else.
So you need to cancel that ticket and get an infant ticket for your daughter.
