Norahbennette This really is getting ridiculous, there are over a million muslims in Britain. The proprotion involved in crime or terrorism is minute, well less than 1%. If you limit it just to Pakistanis, the number of ISIS terrorists who come from Pakistani is very small. The majority come from north africa and the horn of Africa, quite a number are of Afro-Caribbean and European origin.
Would you be equally worried if your SiL was Irish? The number of Irish people, on both sides belonging to nationalist and protestant paramilitaries was far higher, proportionately, than muslims involved with terrorism. Many more people were killed by Irish terrorists, Irish terrorists could be just as indiscriminate in their killing as any muslim terrorist. And the Irish troubles didn't end with the Good Friday agreement. There are still Irish terrorists active and planning bombins and killing.
Errant parents do not have to be muslim and Pakistani to take children on a family trip and and then abscond with them. When it happens the parent is as likely to be French or German or Australian as Pakistani.
I have never heard a grandparent before have a daughter who has been with her partner for over 10 years and is now married to them, who is not estranged from her mother, yet has a mother who speaks of her husband as if she hardly knows him and as if he and his family were some freaks from the zoo.
In a previous era I would say you were reading too many cheap thrillers, nowadays I would suggest you are reading too many right-wing racist social media.
The best thing you can do is welcome your SiL into your family, no matter what the neighbours think. Get to know him as a person, welcome him warmly into your house and life. Remember, he is the father of your grandchildren.
If you have any soundly based reasons to suspect his intentions for going to Pakistan, then talk to the police.
If there were priest in your town being prosecuted for raping children, you would have no worries at all because they would be under lock and key, and certainly no longer in your town. Howeveer, you probably do have paedophiles living in your street and quite a number in your town. Howeve as yet you do not know who they are because they have yet to be dicovered, and they are probably not Pakistanis but nice European people like you. Now there is something to worry you.
I am sorry you sound unpleasantly racist, and sound as if you move in circles that encourage you to be so.
The best way you can protect your grandchildren from all these stories that make every muslim a terrorist, and every visit to Pakistan as full of criminal meaning, is to go open armed to your SiL, welcome him into your home and family and make it clear that as your SiL is valued and loved as your DDs husband and the father of your grandchildren. Try and meet and be open to his family. Their opinion of you now is probably that you are a nasty racist woman, who holds them, their culture and religion in contempt. You have some hard work ahead of you.