Definition of extended family member
Regulation 8 defines an extended family member as a person who is not a family member of an EEA national under regulation 7(1)(a), (b) or (c) and who is either
A relative of an EEA national or their spouse or civil partner who is dependent on the EEA national or is a member of their household
in addtion
There is no limit on the distance of the relationship between the EEA national or their
spouse
or civil partner and the extended family member as long as they can provide valid
proof of the relationship between them.
So therefore evidence of relationship and dependency is the only thing required
Also one of the principles of the eea free movement is that, there can't be a price tag for bringing in family on holiday not to talk of staying. And this is why many British who can't afford the uk cost for love and many are taking the surrinder singh route.
I have no intension of claiming benefits while my parent is here, this cost of this trip I am planing is well beyond what any benefit I may claim, if any at all. So HO need not worry in that regard.