You may want to refer to this discussion for details, and any other made up (non binary) pronouns.
Edit: My story also has humans and robots. But not any old robots. They are called “Reploids”. Like humans, Reploids do have a gender: they can be male, female or nonbinary. In the third case, they use “they” (pun intended) as their preferred pronouns. Fun fact: most nonbinary Reploids are nonbinary because they still see themselves as not just second-class citizens, but separate species from humans altogether. Feeling prejudiced, they choose of their own freewill to label as nonbinary.