My new wife seems to be trying to be a mother to the children of my late first wife and it is making me uncomfortable

This is a very complicated situation, so please ask for any clarification on anything that you may find confusing, I'm not a writer so I may have a hard time expressing all of this properly.I lost my first wife (the love of my life, forever) who I had two children with in a car accident four years ago, and soon after that the business we built together went bankrupt and I had no money to take care of our children, so I had no choice but to leave our sons with my wife's sister and her husband and return to my native country (where my wife and her family are also from, in the Balkans) to work for a family member and send money back for them. I was gone for three years, and in that time I met another wonderful woman, who I am now married too. We have relocated back to the United States, I have opened another business and we have an 8 month old baby.My new wife is a great lady, loves children and is a good mother to our baby, but I am uncomfortable with how she acts towards my two older sons. Of course I want them to get along with her, but she seems to be trying to act like she's the mother to all three of my children. I have no problem with her acting like a mother to the child that she is the mother of, and doing everything that a mother does, but I have observed her trying to set rules for my children (not help enforce previously established rules, like one normally does with someone else's children) and she has asked my sons to refer to her as mami which is the informal and affectionate term for mother in our native language (like mommy, mama in English), they called their mother that when she was still with us, but when they speak about her now they refer to her as our mother or nënë (which is a very formal and somewhat detached word for mother). It's also very apparent that she dislikes my sister in law, who is my first wife's sister, who raised my children when I was away, and who I love dearly. It seems apparent to me that she is jealous of my late wife, and trying to take her role/replace her, which she can never do, and I don't want her to do.I love her, I want her to be my wife now, to be the mother of my daughter and to have a good relationship with my children and our family, but she isn't my first wife, my Fetija and she will never be her. The thought of her trying to replace her, especially in the context of my children, who came from my first wife's body, makes me angry. I feel like it dishonors the memory of my wife.How do I approach this subject to her, to tell her that I'm uncomfortable with her trying to parent my children, with my children calling her a maternal title and with all of this that she's doing? I want her to be who she is, who I love very much, the mother of our daughter (not my sons) and my wife. However, I don't want to hurt her feelings, and I have no intention of leaving her. Maybe it was too soon for me to get remarried, but we have a child now, she left her life in our country to come to the United States, and I do love her and she does love me, so if it is my choice we will stay together.This question is both a relationship and a parenting question, but the children are the most important and the relationship forum on Reddit seems more....vitriolic.Thank you for reading and answering and I hope that your families and children are healthy and blessed via /r/Parenting http://ift.tt/2wpMDBp