is this some sort of insurance fraud?

[Gerbil Lover]

here's the deal. my ex got sick and can't work anymore. he's getting disability payments every months, or so. his brother came to stay with him, and needs a job. but he doesn't have a social insurance number, because he's only staying in canada for a year. the guy that was going to hire him, told him that he could use my ex's social insurance number, but if he does that, my ex isn't going to get payments anymore. so they're thinking of using my daughter's number. she just started working recently, so from what they explained to me, he would be working under her name, and she would have to do the tax return.
i'm wondering is this legal, seems kind of shady to me. what would the consequences be, and is there any other way to help him with the job situation?
thank you