They may not all be together or in same place, 1 on this side another other side. and 1 at the absolute furtherest point away.
kittens are notorious for this crap, getting stuck in tight places.
Mom may not could fit to follow.
But you have a very small window of time to deal with this.
After a few days and you have a royal mess.
and if it gets to that, the odor will always linger faintly.
Not the most pleasant thing to post about.
And I left out a bunch of unpleasant details that go along with all of this.