We're finalising a trip in a few months LHR-BKK (on BA) then BKK-HKT (probably on TG). Our youngest child will turn two between BKK-HKT and HKT-BKK so will require his own seat on the way back.

We're very happy to pay for a seat for him BKK-HKT but we're not going to be taking a car seat or anything like that. It would be fine to have him on our lap for take-off and landing as I know that's technically required, so long as we can put him in the aircraft seat in-flight.

Is that likely to be OK or might it confuse some computer system or safety check? Would the cabin crew be all right with it?

Separately to that, we know we can't check baggage through so aiming to land BKK 09:40, deal with immigration and check-in again for the 14:05 flight to HKT, leaving a bit of wiggle-room. Does that sound realistic for a party of three adults and two children?

Thanks for any tips.