It's pretty simple - I put Drone 1 up to where it had a nice view and turned it around.
Then launched Done 2 and went up and found the first bird and carefully crept towards it.
Because of the very wideangle lens, I had to get them pretty close and they keep randomly drifting around about a foot so it makes for some nervous joystick work.
And because they are so high up, you can't clearly see the separation and have to rely on the screen view.
I'll have to try again when the light is right to improve the composition.