Im set up to click on all 6 computers at the same time (grats Keyclone for the suggestion). I just set my resolutions and views all the same and set the mouse in the upper left then move to the same spot on all computers ..... as my mouse goes to all 6 computers I just click once and ....

Still as I have one group of 4 and one of 5 if the battle ground only has room for 4 then the 5 group won't get in. Or if it has room for 7 just the 5 group will get in.

But if a new BG is starting everyone gets in easy.