Sara65, I've never been on Mumsnet. I'm lucky to have a good relationship with my MIL. She lives a ways away, but we offer her to visit often and send her pictures whenever we think of it.
I do have challenges with my own parents, however. There is a definitely a differing of opinion on expectations. My father believes that grandparents do not have to follow any of the parents guidelines and they their "grandparent experience" trumps my parenting.
He believes vaccines are none-sense ("he had the measles and survived, after all"), that he should be allowed to feed my daughter food she is allergic to ("Doctors today are too cautious") and he manages to criticize every parenting decision my DH and I make, even chastising me for feeding my very small and underweight newborn a few times over night instead of leaving her in her crib for 8 hours like he did (FYI - my mom did not do this, he was just asleep and didn't remember ).
Still, we are walking the line of a respectful relationship because I do want a relationship between him and my children. But I have watch him closely to make sure my kids stay safe, which creates strain and I do not enjoy the visits.
I have to very quietly and covertly avoid letting my father sit by my daughter at meal times to keep her safe. I'm sure some of the MILs here would rake me over the coals for denying him this. But he doesn't listen and I have to keep her safe.
The echo-chamber and defense of MILs or DILs on these sites no matter what, in spite of logic or rational thought drives me crazy.
It seems a great number of posters will defend a MIL, no matter how out of line because she is a MIL. I assume, from things I've seen here that it is the same on Mumsnet.