Should I be the one who contacts my exes side of the family?

Normally I would agree with all the no their loss blah blah blah, however my dear yes we’re opened last week to this, my ex hasn’t bother with the children for months now, I bumped into his dad whilst shopping, and he nearly broke down seeing the change in children, and after standing talking about all things that had been happening he explained that I should allow his son to see said children, with that I stopped him in his tracks and explained I’ve never done such a thing, and that was reason he hadn’t bothers and he had implied I wasn’t allowing access to any of his family, you don’t know what your ex is telling them and you won’t unless you end up in a situation where it’s told to you, with in 2 days of bumping into my ex’s dad my children were there for lunch and loved it, just edge on caution, you don’t know what’s being said to prevent that contact…