Just position your companions well, avoiding placing them near the edges of cliffs.
I wish it was true.
Sadly, my experience say it dont really matter where you stand ... i spend litteraly half of my movement speed (12m? not sure) to stand far from edge in Grymforge-Nere+Duergars batte ... and they still managed to shove me to lava. :-/ Im sory, but that is just not fun.
I mean, even if that was true, shove would still be quite anoying ... since when i spend my precious spellslot to put group of Goblins to sleep, i want them to sleep at least one round ... not litteraly to next turn, when another Goblin wakes them up and is still able to attack me. :-/
But it would be at least little more bareable.
