No, your stepson is not a related party.
This is the IRS definition of related parties:
Related parties for the purposes of Code Sec. 1031(f) are defined by Code Secs. 267(b) or 707(b), and include:
Family members.
Family members are related parties. The definition of family members is limited to siblings, spouses, ancestors and lineal descendants. Thus, it does not include aunts and uncles, or nephews and nieces. It also does not include in-laws or stepparents. Therefore, a mother would not be a related party to her son-in-law or stepson.
Importantly, family members also do not include domestic partners.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
