Any third rate travel agent can book end on end if fare rules allow it. If the fare does not allow end on end, its impossible to book on the same ticket regardless of TA skills.
Originally Posted by
Often1
BA puts itself on the hook for EC 261/2004 compensation when it is delayed into SEA causing a misconnect onward.
I'm not so sure that is the case. Metal is what matters for EC regs and AS isn't an EC member airline.