I’ve only just seen this, sorry Selugi. I’m just trying to work out, are you the grandparent or parent? Years ago, my husband and I did think about things like this with difficult family. I wouldn’t advise it if you’re the grandparent, it would give the parents more ammunition with which to beat you. If you’re the parent, then it could affect the way your children view it later on. We just kept our distance as much as we could, until eventually we moved anyway. I’d be interested to hear your story though.
1. If you go to court, and you are unsuccessful, there is a very real possibility that you will never be able to have a relationship with your GC until they are adults. You need to consider what you have to lose in that regard.
2. Court is expensive - for both you and for the family. If your children aren't well off financially, that could be food taken out of your GC's mouths. At the very least, it's going to use up resources that could go towards other things.
3. Court is extremely hard on people. Your GC will feel the stress in the family, even if they aren't sure what is going on. You need to consider how that will impact them as well.
4. Access can potentially affect future plans. If you have an access order, that's time that your GC won't be able to go with their Scouting group, go on a sleepover, spend Christmas with their family, go on a vacation, etc. If their parents need to seek employment elsewhere, that becomes more difficult as they have to stay close.
Bottom line: you need to carefully consider whether court is going to get you what you want, and what the impact will be for your GC if you go to court. What is truly in the best interests of your GC?