Do not want to look after someone's DC

OP you are not insensitive or selfish. Your DH is a total twat who has volunteered YOU to care for his nephews child. It's not your role to care for this child it's the parents. I cant phathom why they had a 2nd child when they couldn't even cope with 1.

This is about your DHs ego maybe if he actually did the childcare he would realise it's not fun but really hard work. Your kids are at an age you should have more freedom not less. If you can't reason with him leave him to babysit. He offered so he can take the responsibility. You shouldn't have to leave your house but in this instance I firmly suggest you make alternative plans with your dcs everytime he offers you to babysit. He needs to learn a lesson and your dcs need to not be the default babysitters when your not there. It's unfair on you all and your DH won't listen to you so show him it's not fun being dumped with a 6 year old to care for.

No, put your foot down and keep it down.
This happened with a school mum when my kids were in primary, her son “ really loved coming to our house” so much so that I was hosting her dc every weekend. And my child didn’t like staying at theirs and refused to go. It went on for a year until I said no and kept it at no.

YOU'RE selfish? He volunteered you for an unpaid nannying job!

That explains it a little more.. but then really your DH isn't helping his nephew at all, he's helping his nephew's wife?

I feel incredibly sorry for the child, they're being sent away from home because their parents find it too 'hard' to look after them, makes you wonder if they are being neglected the rest of the time as well.

If your DH leaves all childcare in your hands then I suggest rather than playing chinese whispers like this you need to cut out the middle prats and ask that Nephew's wife asks you directly if it's convenient, rather than asking your DH, it's no wonder he's agreeing to it because he looks like the good guy while fobbing all the work off to you, if you do it this way you can control if or when you are prepared to help out.

Please don't punish the child out of spite of it's parents though, you said earlier if it was your family you'd do it no question, and the poor child can't choose who their deadbeat parents are, the time they spend with you may be the best times the child has, but only you really know if any of that is true or not.

I don’t want to suggest anything which will add to any difficulties in your marriage but what do you think would happen if you did (as others have suggested) just take off the next time this child gets dropped off, or before? Would DH cancel? Would he get really cross that you’ve left him with the child and sulk? Maybe he’d be expect your 2 DC to take over? I think you’re more than entitled to at least warn him that your friends have invited you/and DC out over the next few wknds and, as has already been suggested, leave him to it.

Then I really have to ask - why is his nephew not stepping up and parenting his own child? OK, his wife is tired - but he is THERE. He's an adult. A parent. Why is your husband infantilising him, not allowing his nephew to learn how to be a father?

I would be so pissed off with all this, I'd be giving all three of them the rough end of my tongue. Mother for sending her eldest to you without considering you, father for not supporting his wife and parenting his child, and husband for being a feckin' White Knight Riding To The Rescue twatface. He's preening like The Big I Am, whilst not stepping up himself. Nope. I would happily embarrass him in front of his family by putting my foot down to them. Bypass your husband completely, and tell this couple you are not their skivvy and this is stopping NOW.

He's the insensittive and selfish one! What a horse's ass!

I really think you need to go away for a weekend so that he gets the full brunt of caring for the six-year-old. Let him see what he is asking you to do. Don't lay in any food or make any prep whatsoever. Let him handle every aspect of logistics. If the kid ends up hungry, overtired,not having a bed prepared, etc., that is on him to solve.

Is there any chance that you and the other kids can get away? Or at least, you?

He is highly selfish and insensitive. He wants the kudos of helping out while putting all the work on you and doesn't care the impact it has on you. Do you have family or money for you and DC to stay somewhere else next time he offers you up to help? Then keep doing it till he gets the idea. If he wants to help he can help. He doesn't get to volunteer your time.

How dare he call you selfish when he is volunteering your time and energy not his own. If he wants to help her HE can help her, not you or your DC. She is really selfish too. Cancel every time or leave until they both get the message. They don't get to decide what you should be doing with your time and energy and your life.

I swear the same thing crossed my mind!!!

But it's probably highly unlikely.

I'd love to know how long this has been going on for, is it just since their second child was born or prior to this?

This is a weird and unusual situation, where a man is insisting that his wife regularly looks after someone else's child especially a "great-niece". DH is same age-ish as the childs's father. Is it remotely possible that DH is the child's actual father?

You've done the hardest bit, you have said no. Stick to your guns. You owe it to yourself and your own children. It's not normal to be landed with someone else's child. The parents have to step up and sort themselves out. Daddy(nephew) can mind his own children while mummy has a rest.
If the 6 year old is upset, it's the parent's and DH's fault for creating the situation.

@howan I totally get where you are coming from. I’ve 3 dcs who are now all primary and secondary aged but can do so imagine this situation with certain people, particularly my bil who now has a way younger girlfriend and omg good luck to them if they have kids and expect any help from us!
They never even look at our kids when visiting…
Anyway for all the people saying just let dh do it and you go out , the op shouldn’t have to leave her house !!! It’s so, so cheeky , also expecting your dcs to entertain the dc. Especially when they didn’t help you when you had small kids . I never get that tbh, like why don’t they make that connection! It’ll be the baby once it becomes a toddler next ….

I agree the child is going to end up at your house more than there own if this is not nipped on the bud. I have watched this unfold in DH family and feel heart sorry for the child who is rarely at home because the mum and dad "need a break" . The unpaid babysitter never gets a break.

slightly off topic, but hearing people refer to babies/toddlers as 'brats' really makes my skin crawl, I think it's a good thing your arrangement was short lived.

Apart from the burden on you, if I were your 12 and 14-year-olds, I would be really irritated at having a random 6-year-old in the house every five minutes. I was 14 when my mum was childminding kids that age, and I just found it to be a pain.

Your DH is being a giant twat about this.

@DeeLusional Because the OP also referred to the 14 & 12 year olds as "MY children "

This! It's unbelievable that these three entitled grifters think they can stick you with the childcare.

Why did your nephew's wife choose to have another child if she found one such hard going? Her problem, not yours. You do have a DH problem, though.

Your updates still don't explain why DH feels so obligated to help?

Is the Nephews wife the mum of the 6 year old? Does the nephew work away? Nothing you have said so far has explained why your DH would feel like he 'needs to help' to the point where it's every weekend.

I can't help feeling there's more to this then you're letting on...

Another way round it is to say the teenagers want paying for looking after the 6yo as they’re thinking of starting a babysitting sideline and given the 6yo enjoys their company so much, they’d love him to be first child. Bet they’d stop sending him round so quickly then…

Why assume that the DCs are not DH's DCs? Yes she says they aren't really "cousins", but that may just mean that they are some sort of relation that the family calls "cousins". OP, are these children DH's sister's children? Or is this girl child possibly a lot closer to DH than anyone knows.....?

@howan so why cant the child go to stay with your husband brother or sister, whoever the grandparent is??

Your problem is with your DH, not the family member or her children. She is accepting help from family members that - as far as she knows - the family members are happy to provide. The BS about how she shouldn't get help just because you didn't just makes you sound awful, honestly. Lay off that. The family member is not at fault for your and your DH's partnership and communication issues.

That said, it sounds like your DH is communicating to his relative that your family is happy to host the 6 year old when you are not, and you are not obligated to help out family without boundaries. Have a straightforward talk that if he wants to keep this offer extended then you will not be helping look after the guest and that your teens will be told that they're free to make their own plans. Or agree on a frequency of visits that feels manageable and he must communicate that to his relative. It's not acceptable for him to volunteer your services against your wishes.

Every single time. When it's his problem I bet it will stop

Helping out with the 6 year old occasionally is a nice thing to do. Lovely that he has a good relationship with his big cousins etc.

Having him sleepover at your house every weekend when he has 2 parents and presumably no pressing reasons to need extra support (severe illness, disability or something) is ridiculous. His own parents should be looking after him!