Dependant relatives - cousin, brothers, ets

Hello all. I want to ask if UK still recognise dependants relatices such as cousin, brother, etc for visa purposes of a british or settled person. is there a particular form they can use and what are the eligibilty requirement. Any information will be welcomed. Thanks all.

What is the purpose: To settle? To visit?

vinny, the purpose is to switch from tier4 student to family, based on the fact that the mother who was eailer the sponsor on tier 4 has died, so i am the one supporting him for now as my dependant, and he is my cousin. I am british.

See also Adult dependent relative.