+1 on buying a seat. We stopped traveling with our son at 11mo as a lap child (at which point we always did 64AB unless we were in F). But since then, we’ve always booked him a seat and taken the DFG configuration downstairs in J (you can’t book a bassinet position even for a ticketed one year old) though we have never had someone assigned to E. In one case we moved to EFG and someone moved into D. But we monitor it to make sure some single parent with a baby who wants the bassinet doesn’t book it.