vices are voices, pretty much.
it will be very hard to remove the kids completely from your track.
you should keep experiemtning with eq, BUT it wil only get you so far, and it wont really remove the kids.
the next step wil be to edit some fill or atmos onto another track,
and then cut or volume graph the sync dialogue out when ever the actors aren't talking.
you could try using a noise gate to do this, but it wont be as accurate as doing it manualy.
it's not great.. watch an old episode of Rockford Files to hear some pretty clunky gating.
best would be to find quiet pats of your location sound and cut them into the sync when the actors arent talking,
then MASK the kids with some other atoms that inhabits roughly the same audio spectrum
birds? squeaky metal in the breeze?
nick