Advice urgently needed

Mrs B is on a stamp 4 based on her irish born child. She has 3 other children 2 of which are adults and were issued stamp 3 (no work,can't engage in business ,no recourse to public fund)
The 3rd is still a minor . The issue of the adult dependant not being able to work is a massive burden on Mrs B. No grants for the children, no work. Its devastating..Is there any other way to change this stamp 3 to 4 ? Can anyone advice if Mrs B Children can apply on their own right and how?

Thanks a lot.