Absolutely do not. Take it from me. It backfired enormously and 25 years later I am the one being scapegoated and it was brought up by MY CHILDREN (who were not even born then) as an example of my horribleness. Do not do it!
It takes an extremely rare, self aware person to be open to criticism. The majority of us experience shame, defend ourselves instinctively and the sitution gets worse.
I noticed how, when the relatives told my children of the vile actions of their mother, there was not an ounce of self examination of their part to play. They were just the victims, 30 years later.
And the children were told, even after I had apologised for my part to play (several times). All we can do is take responsibility for ourselves. We cannot change others, so don't try!
The best thing you can do, is to look at what they do that upsets you, ask yourself whether it is any of your business or none of your business (the above situation I describe was NONE OF MY BUSINESS I was being triangulated and I should never have got involved) and when you have worked that part of the puzzle out? Set calm and firm boundaries in the face of what is your business (their personal treatment of you).
But if it is about favouritism or unfair treatment or inheritance or any of the relative type things that come up? Zip it. They won't hear you, will get angry, will recruit others and it all escalates.