I hope someone here has a legal background to help me with a specific question. In my story I have a building, owned by A, fully private. In it, there are vaults, one of them fully owned by B. The vaults are all fully surrounded by the premises, owned by A. Now the police has a search warrant for B's vault. Can A legally refuse access to his premises? In other words, does the police also need a warrant to enter A's premises in order to be able to get access to B's vault?