Attributing income to ex?

I go back to court Monday fighting for custody of my daughter (12) who lives with me full time. My ex is fighting but it’s really about the money she’ll lose and unfortunately not because she cares for our daughter.

She is claiming hardship while I’m claiming she has unreported income. I’m looking for Californina case law or decisions that attribute income based on regular expenses that meet claimed income.

This is really about me being able to financially support our daughter instead of the ex.

Thanks in advance