Cops are swamped with this kinda thing. If they don't see the crime, such as the brother's assault outlined above, and the victims won't talk or press charges, then it's "he said, she said", useless to pursue. BUT, they can take a report.
There's been more than once in my life where the cops later asked, "Why didn't you call us?!" Having said that, for many reasons I hesitate to involve police unless uncontrollable violence is going down in the moment.
OP's disabled and unemployed. Please don't be facile.