Your wife already has seat booked, so other options are out of the question at this point. I think she will do fine. It is first class - baby will be on lap during take off, landing and other seat belt required times. I agree with others about trying benadrl at home first. Otherwise biggest issue will be wife having to get up, but FA should hopefully help. I have always found people very helpful, and my kids much better behaved than I imagined. Good luck!