Help! Bedtime issues with toddler!

Okay, I need advice.

My husband and I have a pretty unpredictable work schedule. He manages a record store usually Mon-Fri 8:30 to 5:30. He always gets called in on weekends or to stay later because his employees can’t do shit on their own.

I usually work from 12-8 pm but most days I come around 9:30 so I can leave early. I don’t work on fridays but have to come in on saturdays and sundays for about 4 hours each.

We have two kids and another one on the way. With our schedule being so irregular it’s very hard to adapt a routine with the kids and being consistent. Our main issue right now is naps and sleep.

On days when one of us is at home, we try to get our 18 month old in for a nap usually from 1 pm- 3 pm and our 3.5 year old at least for an hour and then quiet time or cuddle time. When they’re at daycare we have no issues because they’re in different groups but at home, our daughter will either fight sleep or pretend to go to her room and sleep and minutes later wake up her little brother to play. I’m starting to wonder if she’s getting too old for a nap but I really don’t want to change whatever routine we can have with them.

Since I come home late at least a few times a week, I often miss bedtime (which is for them usually between 7 and 7:30) and they always wake up in the middle of the night because they “miss mommy”. That breaks my heart honestly.

So I guess my two questions are... should we change their bedtime a little later so I can spend some more time with them at night? And how do we explain to our daughter that her little brother needs to nap and she needs to stay quiet/in her room/ nap?

Thanks!