The fact that a marriage is a second marriage is much more important to estate planning than many people realize. Many people who have children from an earlier marriage make the disastrous mistake of leaving their entire estate to their new spouse, trusting that the new spouse will look after the children in his or her will. If you only knew how often that trust is misplaced, you would be horrified.
Time and time again, parents who fear insulting their new spouse by suggesting that they might not look after the step-children create situations that lead to their children receiving nothing. A reader recently wrote to me and described that situation. All of her mother's estate went to her step-father, and eventually to the step-father's live-in girlfriend. It is extremely unlikely that this is what the reader's mother wanted. Her question and my response are below:
"When my mother passed away she left no will and her estate went to my step father. And now that he has passed away, I received a copy of the will 6 months later from the probate lawyer. In the will I was deliberately left out and the person who my step dad was living with got it all, as well as having convinced my step dad to give her power of attorney. Now the reason given was that I had caused him grief allegedly and that he hadn't seen me in a very long time, which is an outright lie. Can I contest the will?"
I am assuming that your step-father did not adopt you, as I'm sure you would have said so if he had. While adoption would not necessarily change anything, it would at least give you the legal status of being his child rather than his step-child. As cold as it may seem, step-children don't have legal rights to step-parents' estates, even if that step-parent raised them from babies. So, you cannot contest the will based solely on your relationship to him.
Legally, your step-father doesn't need a reason to leave you out.
To change the topic slightly, you have suggested that the live-in woman "convinced" your step-father to give her power of attorney. I don't know how you could know it was her idea and that she persuaded him. However, it does happen, and it suggests that perhaps she also persuaded him to change his will in her favour. If she did convince him to change his will, that is something you can contest. It is called undue influence.
The problem with a lawsuit like that is proof. How do you get a copy of any earlier will that left something to you? Do you even know for sure that there was an earlier one? How do you prove your step-father was pressured? This is really difficult stuff to prove. It appears his live-in is prepared to battle that out with you, as she has already given a story (that may or may not be true) that is intended to support the idea that your step-father had a real reason to exclude you.
If you honestly feel that your step-father was coerced into removing you from his will, find a local lawyer who specializes in estates, and go in for a frank discussion of what it would take and what it would cost.
It's really very unfortunate that your mother did not make different plans. Obviously she trusted her husband to look after you, as she did not make a will of her own. She is not the first spouse to make the mistake of being too trusting. Most lawyers who deal with people in second marriages will strongly suggest ideas and plans that ensure this doesn't happen to the children of the first marriage. I know this doesn't help you now, but I want to make sure you realize that your mother would surely have made a will leaving part of her estate to you had she known that you'd be treated this way.