I think the problem is the baby. I’ve never written a story with a baby before, and maybe there was a good reason for that.
I had a bunch of scenes with the baby, all the way through from its first appearance (crying, annoying some other characters in a somewhat amusing way), to the end, where it was revealed…
The problem has turned out to be that, particularly in an Agatha Christie type mystery where the characters are all stuck in one place together, you have to account for the baby at all times. You can’t have it go outside for a smoke during a scene where it would be in the way. It could doze off for a while, but I understand that’s very temporary, especially during a storm with thunder and lightning.
Plus, in a mystery story, a baby has very limited usefulness. It can’t commit a murder, and it can’t solve one. You certainly wouldn’t want it to be the victim, and babies make very unreliable witnesses (unless you do a “what the dog did in the night-time” thing, but that’s way overused at this point).
So, the baby is out. Sometimes you have to kill your little darlings, or at least boot them out of your story.
As W. C. Fields said, “Never work with animals or children.”
(Daphne growled at me when she read that, so I had to reassure her that of course I wasn’t referring to her.)