My husband and I had our wills done last year. It took us about a year and numerous discussions to decide what to do.
We only have one child and at any given moment we don't know where he is. Currently he's traveling across the country with his dog. He only touches base once every few months and it's always to complain about how his life sucks.
Our son was married and had two beautiful children but decided he would rather drink and do drugs and he abandoned his wife and children. My daughter in law and I are very close and during their brief marriage she shared some really ugly stuff that my son had done.
My husband and I have literally spent tens of thousands of dollars trying to help our son. Everything we have every given him, he's trashed or sold. He has treated us with such disdain and disrespect.
All of this coupled with the fact he has abandoned his children helped us to make a very difficult decision.
We put our entire estate into a trust for our grandchildren.
My husband and I have worked very hard for many years to have what we have and we know if we were to leave it to our son that he would drink and drug it away and I do not want to be the avenue for him to further destroy himself.
We chose a revocable trust rather than an irrevocable trust, that way, if our son starts to make better choices and live more responsibly we can always include him. That's the nice thing about a will, you can always change it. My husband and I will revaluate yearly to see if there are any changes that need to be made.
We discussed this with our attorney and she told us that if we included him without knowing how to contact him, that whatever we left him would just sit in limbo.
We also had our lawyer process our advanced directives and power of attorneys.
A side note, even when an estate is equally divided between siblings there can still be strife. I know this first hand in dealing with one of my sisters. She felt she was entitled to more than an equal split even though our father's will was very specific.
Good luck with your decision.