Fails at the first hurdle for me as when you set up the trip you enter Departure/Arrival airport and then you're supposed to choose from a list of flight numbers
Seems okay for FAO-LHR , but it doesn't give any numbers for FAO-LCY ( also a bit weird you'd select the date before choosing the flight number, but anyway ! )
Hard to know how you'd use it for travelling with kids either as there seems no option to add any details other than your own ? [ to complicate things one of the kids is on a different booking ref, but haven't even got to that stage ]
Seems like an interesting idea, but not really ready for prime time for me anyway ... The online tool that they were using for document submission via BA.com for outbound flights seemed to work well, but that looked like something they built on BA.com , not a 3rd party tool
EDIT. - I found something in it to add travel companions so maybe that works for the children .. but the lack of a flight number for FAO-LCY is still a blocker