To want DH to consult me before making childcare plans

I don’t think it’s unreasonable to expect your spouse to talk to you before they arrange for your child to sleep over somewhere outside the home! Especially when it’s the first time so they must be quite young…!

He shouldn't have to think whether his parents already have his niece on that day or not.
I can't imagine having to keep track of your siblings caring arrangements, and it's not really any of his business.

The issue is that his mum/parents said yes, when really they can't. So it's a conversation to have with all of them:

• either your husband hasn't clearly stated what he needed (e.g. from 6 pm at X location)
• or his mum said yes when they weren't actually free.

They both need to better communicate, and if it's not clear to him your husband needs to better understand what's required when setting up a babysitting arrangement with his parents (or a babysitter).

But taking the responsibility out of his hands is not the solution.

Surely the question should actually be why didn't MIL use her words and suggest another night? If she agreed then whether she's tired or not is on her.

He shouldn't have to run child care past you. If you're annoyed with anyone, be annoyed with MIL for agreeing.

I don't understand. Surely if it is such an issue for MIL, she'd have said no? Are you sure this isn't about your anxiety about him sleeping over for the first time?

If that was me - I’d say thank you and crack on planning a nice night out.

surely MIL could say no if she doesn’t want to do it.

let your DH be a parent and an adult without having to get approval from you first

You need to relax.

Do you run everything past your husband?
I think you overthink this being anreasonable.

DH: Hey mum, can you have son overnight on x date?

MIL: Would love to but looking after niece that day, could do y date instead?

DH: that'd be great

No need for you to be involved at all op. A need for other adults to communicate like normal people.

this is assuming mil hasn’t chosen to be knackered over having both a Friday & Saturday evening taken up babysitting.

He’s more then entitled to arrange childcare for his child as well.

His mum is also more than entitled to say no.

Have you spoken to MIL, she may have been exhausted but I would rather babysit once than twice in one week. I’d take being tired over having 2 nights looking after kids. It’s abit of a coincidence that the 2 times he asked as clashed with SIL. So I assume they’re always babysitting for SIL or the mil has been asked and she’s preferenced the date, either way

as for SIL. So what her daughter had to forgo an activity. Your mil is grandparent to both kids. If routine is so important she’d take no babysitting from anyone. When I’ve babysat for family members n the past I’ve tried to adhere to the rules. But if my nephews kept getting up I wasn’t going to go all super nanny on them. I’d tuck up next to them & watch something. When my kids where looked after by family I expected a little routine damage. I might have a crappier day the next day but it’s a price you pay.

His mother should have said sonething!!

Just change the night out to a different night?

YABU to require him to check with you every time. You'll just be creating a rod for your own back.

But I do think it's reasonable to tell him that you don't think it's fair on anyone for PIL to be looking after children from two families at once, and to avoid booking on days when they're already committed. It might also be worth having a word with his mum and saying the same. She might feel like she can't say no.

He shouldn’t have to check with you per se, however, he should have the intelligence to realise that his mum will be knackered after a full-on day with two toddlers, know his own child’s routine well enough to know it could be fucked up by messing about with it to this extent and pick another day.

By simply choosing a different day, he won’t have fucked off SIL & BIL, or potentially knackered his mother out, his child would probably find the evening easier, and you’d be a lot more chill about going away.

Does he always put his wants and needs before others?

Why doesn't your MIL say no? I think this is on her to communicate not your DH to mind read.