I think my best hope is that I could change what “other” means in my use - and then have more “others” available, so that you don’t have to program what relationships are.
I’m also surprised that when I put someone in as an “other” that they aren’t listed as an “other” on the opposite person.
Another problem I have with relationships is the parent/step parent/adopted child links. My family has a complicated relationship, so both my husband and I have biological parents, adopted parents, and step parents. I also have a child whom I gave up for adoption who I have a relationship with - his adopted parents divorced, so he also has biological parents, adopted parents, and step parents.