Basically, I try and avoid the situation.
Adults partnering kids help, so arches are similar (if somewhat
Suggest small children don't partner each other.
Don't use such dances.
Use dances with kids going thru arches made by adults.
Tell them it's ok to just hold hands up and pretend to make an arch.
If everybody is having fun, it probably doesn't matter much :-)
Watch the set dancing across the hall at the back of the room