3rd country Family member reg 7 1 (c) - whose support counts

Hi everyone
I have an Albanian couple with failed HRT. They were given PSS as family members of their daughter in law who has Greek nationality. Her husband (the couple’s son) is British now and afaik he never exercised treaty rights in another EEA country before Brexit.
I am not sure now whether they can establish dependancy through material support provided by son , or if only support provided by the EEA national daughter in law counts.
If I understand regulation Reg 7 1 b for direct descendants over 21 seems to state expressly that they can be dependants of the EAA national or their spouse or civil partner, but i am not sure whether the same applies to 7 1(c) which is worded slightly different.
I am supposed to call the Citizens Advice immigration helpline for adviser, but I just cannot get through to them.
Is there maybe any caselaw on third country parents- in - law & dependancy?

The wording may be different, but the effect is the same - it doesn’t matter which individual member of a couple is providing the support to the dependent family member(s) in the ascending line (and in the case of financial support, where a couple will generally pool their financial resources, it would probably be very difficult to disentangle which of them was the provider of support anyway, though that is by-the-by).

What matters is that one member of the couple is exercising one of the EU free movement rights of residence - i.e. are they a worker, self-employed person etc? In your case that can only be (and only ever could have been) the Greek daughter-in-law. Unless I’m missing something, the son, before naturalising as British, was also a 3rd country national - so he couldn’t have exercised those free movement rights of residence, either in the UK or in the EU.

Thanks for that. Luckily, there is no problem with the daughter in laws freedom of movement right, she has worked all the time since the in laws arrive and still has hera permanent job