If you have adopted your step daughter, thus making her your daughter, her husband is your son-in-law.
If you have not adopted your step daughter, then her husband is not related to you. Some people find it convenient to treat him as a son-in-law, especially if the step daughter became part of your family when she was a child. Although a relatively recently invented term, and not widely used, some like to apply the term "step son-in-law."
He is my stepbrother.
The husband gets the house.
Your daughters husband is you son-in-law.
3 daughters with her husband who was divorced and had eight of his own at the time of marriage. She is step mother to them as well.
He didn't have any blood related daughters, but he had step daughters
Your step sister's husband is your step brother-in-law.
Beverly Sills had three step-daughters, born to her husband Peter Greenough in his previous marriage. There names are Lindley, Nancy and Diana. Sills had two children of her own with Peter: Meredith ("Muffy") and Peter Jr. ("Bucky"). Source: "Beverly, An Autobiography" by Beverly Sills.
Your mother's new husband is your step-father and you are his step-son or step-daughter.
Your grand daughter's husband is your grandson-in-law.
Uncle
Your daughter's husband is your son-in-law.
Your mothers husband would be your step father and you would be a step son or step daughter.
Mary Lee Cantwell's husband was literary agent Robert Lescher. They had two daughters - Katherine and Margaret.