Upon further investigation it appears that focus is client side only. So there really is no sharing it.

The best I can come up with for automatically doing it is to have something like the following:

1. Hit F3
2. W3 executes /target focus
3. W3 whispers to W1, W2, W4 "assistme"
4. W1, W2, W4 execute /assist W3

This brings it me to the point, can code switch targets automatically? or is that restricted? Off to test this one out.

This would still have a round trip latency, but it would at least require only one button to get everyone to switch, and nobody's focus would change in the mean time.