They do impute income. She and her partner shared a couples job, and I was looking on some of the job search sites and they come up with income (for the couple) of $32,000 to $40,000 per year. Plus she told us she was still on Disability. But that could either be a lie to get us to leave her alone or it could be that she's been duping the government and not telling them her real income - reporting it as only her partner's income. She's lied about things like this before, with not telling Disability when she had other income providers living with her.
Would it even be worth it to try to force document disclosure and get her bank records? If she didn't answer the first paperwork (which seems kinda stupid as that means that she loses without even pleading her case) then she could just as easily ignore another request for paperwork. That would mean contempt charges, but it's not unusual for BM's to ignore contempt charges too.