You must file a tax return if you have net earnings from self-employment of $400 or more from gig work, even if it's a side job, part-time or temporary.
you file schedule C.
you are confused about this
(it would be great if I could in order to help boost overall income for the Additional Child Tax Credit)
it's not her income to report it's yours. I see no way this would increase her income nor do anything else that would increase the credit.
