Well the reason that Dumbledore makes Harry go back to the Dursley's every summer is because Petunia is the last relative on Lily's side. And in order to complete the old magic has to call home a place that has Lily's blood.
But that still leaves James's family. He couldn't live with them because they have none of Lily's blood in them. So my thinking is that there might be some other family that we might find out about.
But that still leaves James's family. He couldn't live with them because they have none of Lily's blood in them. So my thinking is that there might be some other family that we might find out about.