trace along the family tree, one step at a time, and then concatenate shortened forms of each stepwise relationship. the shortened forms simply take the first syllable of existing basic kinship terms.
example: your mother's sister's son's daughter would be your mosisonda
What exactly is considered basic here? Do terms like “half-sister”, “step-mother”, “godfather”, or even “grunkle” count? Would a stemomo actually be a fawimo? Would a hasis be a fada, or perhaps a fathexda for specificity? Are we calling the Godfather go now?
the only downside of this is that NaNoWriMo would have to rebrand because now that's probably a word for some very obscure familial relationship
(and yes, i do constantly say things like "my mom's brother" because "uncle" is just too ambiguous)