This was easy for me to address as a divorcee and remarried. My ex husband remarried a wonderful young lady that loved our child very much. The new wife's family adored my daughter. It seemed only natural that given so much love from that family that my daughter when staying with her father would call his new wife Mama. I never felt a hint of resentment. My only thought was thank goodness she had someone in her life that she felt close enough to that she could call her mama. The other alternative of a step mom that didn't care about my child was not an option I wanted to have to consider.
If your child can be loved enough by a step parent to call them mom or dad, I say congratulations. You are one of the fortunate parties in a divorce/death to have a loving parent come in to your child's life. A child can not be loved too much and to have the love of the step parent and their natural parents only adds to their sense of security.
I can't imagine why anyone would not want their child to be loved enough by a step parent to feel comfortable calling them mom or dad. If you put your love for your child before your own feeling of jealousy, you will be happy for the extension of love being added to your child's life. Having a step parent force a child to call him mom or dad is another issue completely but to call a step parent mom or dad out of love is a gift for all concerned.
How many horror stories over the years have you heard about horrible step parents. I had a horrible step parent and wouldn't have dreamed of calling him dad. I was very thankful that the new step parent in my child's life was a kind and loving parent to my child. It was always with no hesitation that my child went with her father for visitation because I knew she was going to be loved and cared for by both her dad and step mom.
It has been years now and even though my daughter's step mom eventually divorced her father, they have remained close and my daughter still calls her mama. Not only did my daughter gain the love of this lady but also that of her extended family. How can anyone want to prevent that kind of love from being a part of their child's life. The benefits of having this loving relationship have been way to enormous to have ever resented my daughter calling another woman mama. I am thankful to this day for all the love my daughter has gained.
Open your hearts and remember if your child feels loved enough to call their step parent mom or dad, be thankful and not resentful. It's much better to share that title and know your child is loved and safe than worry about an abusive step parent.