Welcome to FT,
samual1985.
Originally Posted by
PPgold
1. wait till -24hr (on-line check-in opens) try and bag two seats together, by swapping around your seats from the online seal selection
A little tip presuming your partner and you are on different PNRs (bookings) and that you don't decide to pay for your seats but instead try to get them together when on-line check-in opens (and you may wish to sit there waiting for the clock to tick-over!

):
As your browser can only handle one session on the BA website at a time, even in different tabs, it can be helpful to have two separate
browsers open at the same time (i.e.: one Firefox and one Internet Explorer). This way you can both select seats together without having to exit the booking and enter a new one.
It's a small chance that someone will bag the seat you were looking for in the few minutes it will take you to change to the other booking, but if it gives you peace of mind then it will help.
Or use two computers, of course!