What's the etiquette?

It should be a please to look after nieces and nephews
I use to look after my nieces and buy them lunches 😅

Just keep in mind that whatever you choose to do now you probably 'should' do every time they look after her, so keep it manageable for yourself. Also, it's family! I would never expect to be paid by family when looking after their children

I think it depends on circumstances.

For instance, if my daughters aunts (she only has 1 uncle and he barely even leaves his house) babysit my daughter, then we say thank you and ensure that we have accommodated them in any way possible (snacks, drinks, etc). We have babysat for them multiple times and still return the favour as they all have children too.

If her only childless aunt babysits then we pay her as we can’t repay the favour. same for our adult niece (she’s 19). She also has no children so we can’t repay the favour. She always tries to refuse to take the money but we don’t allow her to leave without it.

No one ever expects to be paid, and they would happily do it because they love spending time with my daughter. They always offer to babysit. But I just think it’s nice to show them that I appreciate their time.

I'd be offended if I offered to help and then got offered money. But everyone is different x

Our family do things back and forth for each other when the time is needed and not everything needs to be “paid back”. Sometimes we do sometimes we don’t, but my sisters looking after my boy i say thanks but keep that in mind for when their bdays come or something. Last time my sister came to get a bag of rice I asked her for free movie tickets in return (she gets them from her work but she never goes movies so she’s accumulated so many lol). It’s just back and forth w us. Or if they mention they wanna see a movie/concert you can surprise them w tickets etc. just leave it for when the lightbulb clicks, I think. You don’t have to pay them back immediately. Just pay it forward some day.

I would say thanks and maybe buy flowers or fancy chocolates. Something small but thoughtful.

I generally ask what they'd like for lunch/dinner (whatever meal time they're sitting for) and make sure thats in the house. But generally we help them out when they need

I was never paid for looking after my niece, it was a privilege to be asked and trusted to be her sole carer.
If they do it several times, then I would say an extra present at Christmas time just from her to say thank you.

I always offer to pay my SIL. Mostly she just scoffs at me and doesn’t take it, but if they’re doing me a favor I would pay someone else for I try to honor that.
But I’m coming from a family where boundaries were often crossed in that regard, so I’m a little hyper vigilant about making sure my people don’t feel I’m taking advantage of them. Really it’s so different situation to situation so trust your gut! But I agree to decide now and be consistent and do the same thing every time they watch her.

If you want it to be a regular thing, what ever you do this time you need to be able to do it the next time, and every time! A thank you, and a bottle of wine (no more than £10!) would be a nice touch, but equally they shouldn’t want anything in return as the time spent with the little one should be the gift in itself!