Adult social care - financial assessment

My son is an adult with severe mental impairment (SMI). He receives adult social care at home (morning/evening visits).

I am his mother, his full-time carer, and a pensioner. I live with him because he cannot live alone (due to his SMI).

He is the sole leaseholder on a social housing owned property, which has a mortgage & rent each month to pay.

The adult social care financial assessment calculation has reduced the household-related expenditure for mortgage costs by 50% because "two adults live at the property".

However, I cannot find any reference about the mortgage costs being reduced, when calculating the financial contribution for adult social care at home, because two adults live at a property.

Has anyone had similar experience?

Thanks in advance.