Dd’s Ex wants to take DG abroad- ex so irresponsible

That is all evidence that your daughter should gather to use against him if it goes to court.
Nobody in court will care about fairness. They will only consider what is best for the child.
That may be that he does only get to holiday abroad with his mother because his father is not able to support all of his needs.

Only the unmarried parent with PR can apply for a passport for the child.

My DD and ex never lived together. Stupidly she let DS have ex’s surname and he went on birth certificate. Ex didn’t want to know DD when young. Ex even abandoned good local work to play in band on ships for 3 years. DG hardly knew him. Now ex can influence DG he went for custody. Fortunately Judge just gave access but the holidays are such a mess. He’s reported DD to job centre (she has ME) and was managing a couple of hours volunteering. He reported her to Social Services over numerous issues. All fictitious and dismissed. He reported me to Police because I took his phone out of his hand to turn it off after he was shouting abuse at me in a car park and he got his mother on phone to join in. Police dismissed it saying he had an agenda. Not a pleasant man. I seriously worry about his influence on a vulnerable young boy.

Not so sure of a letter from absent parent? D and I have taken GC abroad without letter of consent on several occasions.

I think the problem arises when the name on child's passport is different to that of parent they are traveling with.

I think OP is involved - dd lives with her and us stressed about this. Some hard factual information and advice will help them both especially as ex sounds a bit of a bully and unwilling to mediate for example.

Are they divorced or separated? Does she formally have PR? I assume there’s no passport at the moment?

crazyH I don't know enough about this situation to give a definitive view. I do know enough about children to be clear that what matters is the best interests of the child, rather than whether its 'only fair that the lad spends part of his holiday with his Dad.' The Op's concern is her daughter's worries about what happens if things go wrong and father and son are not in the UK.

As Callistemon's link confirms, each parent needs the consent of the other to take the child out of the country. There is good reason for this. I think written permission from the other parent is needed so it can be shown at passport control at each stage.

It isn't the legalities so much as the emotional pressure in this kind of situation. I feel for the OP but maybe this is one of those (regular) situations where we grandparents need to try and remain a safe pair of hands and not get overly involved.

I don't know the legalities of the situation, but I think it's only fair that the lad spends a part of his holiday with his Dad .

The relationship he has with his child is different to the relationship he may have with your DD.
Is he generally unreliable when has the boy for visits?
Will they be going alone or does he have a new partner who may be going too, who may be quite responsible?

Here is a link which explains what you have to do, ninathenana is right, you cannot just take a child abroad even for a holiday, without the permission of the other parent:
www.gov.uk/permission-take-child-abroad

He needs DD permission to take their daughter out of the country.

Been wondering summermary, would your daughter consider taking your grandson on a holiday out of the U.K.? Or would her assessment be that whoever took him it would be too much of a sensory overload for the little boy? Routine can be vital to wellbeing for people with these underlying conditions and I imagine coping with parents living separately is already a major challenge for him. You sound very tired, I hope this can be resolved quickly in the best interests of your grandson for everyone’s sake.

I have no answers but understand totally your fears
anyone who has not had a manipulative charmer in their life would not understand your concern I would have no more trusted my ex to take small children abroad than fly through the air happily he had so little interest in them he didn’t even want to see them let alone have them on holiday and for that I m eternally grateful

Sorry to hear of the trouble you’re having to live with.
The best bet is for this to go to court.
As you say he will be relentless in his pursuit.
If they do they will likely be assigned a CAFCAS officer who your daughter will be able to speak to without the Ex.
There she will be able to present any medical or educational evidence to support her view. Equally the Ex will have the chance to argue his side.
It will ensure both sides being heard independently and then a non biased well informed decision.

Mediation is something you can go back to. I would ask DD to contact them and ask about this and to make it a condition of his taking child abroad. If he was then to go to court the fact that he had refused mediation would count against him

Agree with Suedomin.

Post this on Mumsnet they have a section for children with SEN
You may find someone who been through a similar situation as your daughter.

Good luck

Does your Dd hold your GS's passport or does her ex have it? That's a key element. It's not easy, though, to take a child out of the country against the wishes of the other parent.

I hope the situation is resolved soon.

I dont think you can stop him taking his son on holiday ,would you want him to tell your daughter she couldn't do it?
Your opinion of him is clouded becuase of his relationship with your daughter but he may well be very different now they are apart.Sometimes people bring out the worst in each other .Try to see it from his side too .

They have been through mediation. Ex talked over DD, cancelled mediation and complained about mediator who DD said was fine. Ex will keep texting, emailing, threatening Solicitor until he gets exactly what he wants.

Regardless of how you feel about the ex he is still the boy's father. I don't know how bad the Aspergers/adhd is but I don't think disabilities should be used as an excuse to limit someone's experiences. I do think it would be better to negotiate rather than go down the legal route. Why not contact the mediation service. It can only benefit the chld if the parents sit down and discuss their difficulties. (I believe they will help GPs as well)

I understand the stress. It sounds as if a conversation with a family lawyer is needed. Wishing you all well.

Sorry to hear this, no answers I'm afraid, just want to show sympathy.