Recourse to Public Funds Saga

[ZINXYX]

Hi good people,
My sister whose husband was British divorced her after nearly 8 years of marriage after bringing her to the UK on a visitor visa, without applying for a spouse visa for her. Her ex husband has relocated to his country of origin. While here he was claiming CTC and WTC but has since stopped.
Because they had a British child she is on the 10 year Family route. She applied for fee waiver for one of the children who was not born in the UK so isn't British yet because the father didn't apply for them.While renewing visa She also included an application for public funds due to change in circumstances.She works full time as a carer, long and unsocial hours yet struggles financially.
Her child was granted the fee waiver and her BRP has been delivered with recourse to public funds. Another BRP has been delivered with her child's name with the same conditions.
We are thinking it must be an error, and that the second BRP should have been hers. Any ideas or suggestions will be deeply appreciated.
Thank you.