I have a bit of a dilemma regarding checking in for my LHR-SFO flight.

Basically, the booking is for 4 adults (myself, my wife and my parents), but I want to fly from GLA (with my wife) to join the LHR-SFO flight, and check my bags all the way through from GLA to SFO.

But my parents live in England, and will be joining us at LHR and checking their bags in there.

Can you do multiple check-ins/bag drops, or do all the pax on the reservation need to check-in/bag drop at the same time?

Any advice on the best way to proceed with this?

Thanks.