Sirius' heir

[Rach]

No: HPFGUIDX 68804

I have a question about Sirius' heir. Phinneas Nigellus said, shortly 
after Sirius' death, that he was the last remaining Black. Who now 
inherits Grimmauld Place? Would it pass to one of his cousins? I also 
wonder who would inherit Sirius' gold left to him by his uncle, and 
the house he had when he was seventeen. Would these be left to Harry? 
Will the order keep their headquarters at number 12? 

Sorry if this has already been discussed.

Rachel