PIP-funded care payments vs UC means test?

Our neighbour's son is due to migrate from ir-ESA to UC soon. He's been left severely disabled after a stroke, no partner, no kids, can't live independently so he lives with his mother who's his full-time carer. Naturally being the home-owner, most bills and expenses (grocery shopping, gas, electricity, water, etc) are in her name and almost none in his. He can manage his financial affairs, so she's not an appointee and the money gets paid to him. So he sends a lump sum payment to her consisting of about 3/4 of what he gets from combined ESA + PIP, partly towards the household bills (in her name) and partly towards informal care costs (she spends dozens of hours looking after him per month, cooking, cleaning, shopping, supervision, etc, yet is ineligible for Carer's Allowance due to "If your pension is £81.90 a week or more, you will not get a Carer's Allowance payment").

Question - Upon migrating to UC many people seem to have been asked to upload bank statements. Money paid to a relative towards grocery / utility bills should be fine (you can upload the bills as proof), but will the UC migration team view monthly lump sums sent to relatives bank accounts as Deprivation of capital / Notional Capital for informal care (paying a relative for 80-100hrs care per month without them issuing a bill / being employed as a professional carer would), or do they make an allowance for this kind of thing (assuming you're well under the £6k limit and the carer doesn't get paid Carer's Allowance)? Does the fact PIP being non means-tested mean you're allowed to use the monthly PIP income for care and the ESA on bills make any difference?

The family asked me for advice but I don't know and apparently Citizens Advice also didn't really have an answer. So does anyone here know what official / unofficial limits, allowances or rules there are, or acceptable 'going rates' for informal care by relatives within the same household when transferring money to family vs means-tested capital checks? Or anything else related that they need to disclose / be aware of at time of migration?

Thanks. I'll be sure to pass along any information.

As an aside from your questions regarding spending his money.,

Mother and son should do an online benefit check, if she claimed carers allowance it would give her underlying entitlement (not in payment) to carers which would give him an additional premium on his ESA, which would possibly carry over to UC as an element.

I also suggest they request a care assessment from LA for Son, he could get a care package and get a PA/care team in to care for him. She could also have a carer assessment.
Especially helpful if he need special adaptions or equipment.

Hi David I did say “ which would possibly carry over to UC as an element” as I was unsure.
My bad I guess.