
Yom Kippur with a toddler is not quiet. He wants breakfast, he wants the one cup you can't find, and he does not care that you hoped to sit with your machzor. So plan the day to ask as little of you as possible.
Do this before Yom Kippur, not during. Sit with your husband and go through the real options:
Settle this in the days before, while there's still time to ask.

Cook, cut, and portion it all before Yom Kippur comes in, so there is nothing to prepare while you're fasting:
You should never have to open the fridge and think.
You already know which toy holds him longest. Save that one for when the day gets hard.

Pick one child-safe room. Put everything within reach of the couch or bed:
Lie down while he stays close. If sitting next to him makes him play longer, sit next to him. You don't have to join in. Being there is often enough.
Feed everyone before they hit overtired, and keep the usual nap:
A real Yom Kippur with a toddler can look like 10 minutes of focus, then a snack, then a diaper, then 10 more minutes. It counts. Prepare what you can, expect to be interrupted, and let the rest go.