To want my sister to have DD if the worst should happen?

Not really. Anyone can say no even if they said yes earlier. It is a huge thing to take on, and it might not be practical for someone even if they desperately want to do it.

We went with a time staged approach. GPs when the children were very young, moving over to auntie and uncle as the children grow into teens and our siblings settled down, start their own families etc. But mainly it's who do you trust to weigh up who is best placed to take care of her at that point in their lives, and decide in her interest rather than their own?Ultimately you'd want the family to come together round the child and decide what is in the child's best interests at the time. There may be factors you don't yet know about, eg child will later develop a serious competitive ice skating career and one of your sisters lives next door to an ice rink, or one sister is well and the other ill and going through a nasty divorce.

Its a difficult one. We didn't have anyone suitable - definitely wouldn't have wanted BIL and SIL, and I felt close friends had too much on their plate, parents too old...
So we didn't have anything legally drawn up. DC are now adults so could hopefully look after themselves.

We haven't picked a specific sister, no reason you should either.You're very lucky to have two good candidates. So leave it with both as options and in the highly unlikely event that both you and your DH die let the relevant authorities decide.

Family Court has the final decision and (as their decision is based solely on the child's best interests) can overrule the will, although it would be taken into account.

What I'd add is that the decision would probably become clearer anyway as your child gets older. In a few short years her own opinion would be heavily weighted and you might anyway find she is naturally closer to one aunt than the other, or that she would suit a particular location because of school/friends rather than it being about the aunt themselves. Kids grow up quickly and the picture will change rapidly.

I mean you can write down whatever you want but the reality is that you can’t just hand over parental responsibility to whomever takes your fancy as the local authority would get involved and make assessments

The solicitor will tell you it's not legally binding.

But it is however really helpful to the authorities when deciding what's best for the DC.

Not the case. Speak to a solicitor. Any nominated person can decline to take on children for any or no reason.

just put your wishes in your own will so in the very unlikely case this situation arises there would be a record of your preference.

Yes, they obviously need to check everything out.

Suitable accommodation
Finances
Whether the person still wants to look after the DC
Whether they're physically and mentally capable
Criminal records
And what the children want will also be considered in an age appropriate way.

Would social services be involved though? If there is a will?

Just don’t nominate anyone.

In the highly unlikely event that you both die at the same time, everyone’s circumstances will be different to how they are now, everyone will have an opinion which may not be the same as they say to you now, family doesn’t get to decide amongst themselves without social services’ involvement.

This is one of those arguments that people seem to have that, in my opinion, are largely irrelevant and unnecessary.

Wouldn't it be more down to who social services thinks would be more suitable?

If the worst did happen, one or both of them might not be in a position at that particular time to look after your DC.

It’s a really tricky one because we are of course always going to trust our own sibling over our partner’s sibling. You say ‘WE are closer’ to your sister but yet he’d still actually want his DD to be raised by his own sister.

I personally think his sister would be better if the worst happened. If she has said she would want to care for your DD it sounds like she could actually give her full attention to her. Plus she actually has experience of raising a child.

your sister could potentially have her own family at some point and your DD would naturally not come first. It would be awful for your poor DD to be pushed out by a brand new baby. It sounds his his sister could give your DD her full attention.

Have either of you talked to your respective sisters about this?

You can write whatever you want and your will and he can't affect that. I would definitely put your sister down and give all the reasons for it and all the reasons why his sister isn't suitable as well. Let's hope it's never necessary but it is better to be prepared.