Maybe a course of dancing lessons would help a clod-hopper like you get those size 11s tuned into what your brain is telling you!
First job, when a bird approaches, is to look at it closely, determine its direction and anticipate the place you’re going to shoot it – then position your feet to achieve shooting it with a smooth swing, and gun mount.
When shooting, your stance should be such that you can keep the swing going for a second shot (if needed) without the muzzles ‘rainbowing’ off the bird’s line of flight.
By all means be ‘aware’ of other birds on the wing but put full concentration into the first shot, kill the bird, dismount the gun and then look for the second.
Unless it’s following the exact same path as the first you must now move those feet: if it helps, say ‘cha, cha cha’ to yourself as you do a nifty bit of footwork at the same time as addressing the muzzles to the next bird.
Practice will certainly help so get in the groove by shooting high driven clays from a tower; get the traps set so that the first target passes to one side, and the second to the other.
To start with, have them thrown on report in order to give yourself plenty of time to readjust your stance between shots.
Dry mounting at home is another great way of teaching yourself to move your feet to suit the bird: stand in the middle of the room and use the line between walls and ceiling as imaginary flight paths.