Good question! This is completely up to the parents and family in question. Some folks just use first names. Some folks use either 'nini' or 'bibi', taken from the N and B of Non-Binary. Sometimes, names can include parental nicknames taken from other languages. There are also options such as 'par', 'per', or 'ren', taken from the inherently gender-neutral word 'parent', and some nonbinary parents don’t have an issue with good ole 'mom' and 'dad'. Be respectful of whatever terms folks want to use, and it should all be good from there :)