Premise: a relationship exists between two people if some-one (subjectively) believes one or both are "significantly" affected by the welfare, attitudes, behavior, and needs of the other.
In any group of "N" people (like your family), the number of possible relationships (R) is [ N x (N-1) / 2 ]. So in this nuclear stepfamily of six adults and three kids, R = [ (9 x 8) / 2 ] = 36 possible relationships to maintain.
Some group member don't choose to relate, and/or don't really like, trust, respect, or bond with each other. Others become good friends over time. In a multi-generational family of 64 kids and adults, there are [ (64 x 63) / 2 ] = 2,016 possible relationships! Many of these people may seldom or never interact - but they all influence each other in webs of genetic, financial, legal, historic, and psychological ways.
To compute the number of possible relationships in your fa-mily, be clear on who you define as "a member." Option - Try this "mapping" technique to gain helpful insight on your family system. Lesson 5 is about building a high-nurturance family over time.