The joke is that she has a whole army of those "changelings" as she calls them but it's never stated how they work for her, probably like a bee-hive of some sort, but the funny alternative would be if she was the "single mother" of every one of those changelings, which is never fully stated in the show itself, which leaves the fans possible answers to fill it out with.
If all of her children were completely capable of independent thought, then it would be a bit troublesome.
But if they function as a hive mind with her as their source of direction, then that's not as bad. Just like social insects in real life, or the Zerg Swarm of StarCraft.
Except the Zerg Swarm is a bit more flexible than real life social insects; the Overmind was the original "hive leader", then it was killed at the end of StarCraft I, and replaced by Infested Kerrigan as the Queen of Blades at the end of the Brood War.
And she makes some "structural adjustments" by replacing the former Cerebrates with the current Broodmothers, which were capable of independence if Kerrigan was ever killed. This of course, would ensure that the Swarm would never be without a leader for long; the weak would be assimilated or destroyed, while the strongest would become the new leader.
I just want to say this. when your species is a shapsifing kind normal rules get thrown out the window and shatter into thousands of piceses. for all we know some hives are like insects others like mamals