@ franklampoon, there is no need to be so ridiculously alarmist.
OP I'm sure your dogs and baby will al get on very nicely with a bit of preparation.
Get lots of the new things out now for the dogs to smell, things you will use when changing a nappy, bathing etc, also set up baby equiptment, pushchair, bouncer, cot etc, so the dogs can investigate it and get used to it's presence pre-baby.
If you can do it without feeling stupid, sit with a doll wrapped in a blanket and pretend to feed, talk to the doll as you would your new baby, so the dogs can get used to you in a new role, (they won't be fooled for a minute, but it will give them a start). While you are mock feeding/cuddling encorage the dogd to like quietly with a tastly bone or a stream of treats, so they see you in this new role as something positive for them.
If you can persuade the parents, see if you can get a recording of your nephew crying, initially this can be played very quietly while the dogs are eating or relaxing, then the volume gradually increased over many days until it is quite loud, ignore the dogs for reacting to it, praise them for ignoring it.
I would recommend you get yourself a good book, try Amazon, I came up with this one, though I haven't seen it myself.
I'm sure other people will come along with more advice, please ignore the alarmists, dogs are very good for children
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