Hi @Jia1342, and welcome to the forums!
One thing that you should probably look in to is something called "Individual Placement and Support" or IPS. I'm told that it's a system where job assigners actually make sure that the employee is assigned the job that's right for them, and aren't just mindlessly sent to some random job because "a paycheck is a paycheck". So if there's anyone who can actually match your bro/sis with the company that actually wants them, I think one of these IPS people are likely your best bet.
The government is looking to roll this system out for everyone, but at the moment, apparently there aren't a lot of these people around and the whole system is under-resourced. So you might have difficulty actually getting an IPS job-assigner to take on your bro/sis's case.
If that doesn't work out, are you employed yourself? If so, could you reach out to whoever got you your job to see if they can do the same for your bro/sis?
I think it's really awesome that you genuinely want to help your bro/sis. With that in mind, it might be helpful for you to check with them to see if there are any higher priority matters they'd appreciate help with, moreso then their employment situation.