I was just wondering if anyone has any experience of this and any advice.
I ideally don't want to give the back story here as it could be outing but what are parental rights on this one if the other parent chose to take children out of the country permanently against the other parent's wishes.
In brief no court agreement, but 50/50 arrangement that has been in place for many years without any particular issues. DH on birth certificate and children share his surname but not hers.
In the past when DM has taken them on holiday DH has not needed to provide any permission and she's been able to do so without any issue. Obviously DH was fine with this but she didn't need to ensure she had anything formal in place. Whilst when DH took them on holiday he needed a letter of permission, copies of birth certificates etc. When she applied for passports DH wasn't required to be part of the process, but when DH renewed the passports he had to go to the nth degree to prove he was actually their father. Previous trips abroad have always been with both parents being happy with this so it hasn't been an issue to get these permissions but there seems to barriers in place for DH but not for DM.
There is a worry that DM could decide to do this and the fact she did not have any barriers in place beforehand increases worry that she could do this without needing permission from DH.