The following facts concern a tract of land in a state which follows general United States law. Each instrument is in proper form and recorded, marital property rights were waived when necessary, and each person named was adult and competent at the time of the named transaction. 1. In 1940 Oleg, the owner, conveyed his interest in fee simple "to my brothers Bob and Bill, their heirs and assigns as joint tenants with right of survivorship." 2. In 1950 Bob died, devising his interest to his only child, "Charles, for life, and then to Charles' son, Sam, for life, and then to Sam's children, their heirs and assigns." 3. In 1970 Bill died, devising his interest "to my friend, Frank, his heirs and assigns." 4. In 1972 Frank conveyed by quitclaim deed "to Paul, his heirs and assigns whatever right, title, and interest I own." Paul has never married. Paul has contracted to convey marketable record title in the land to Patrick. Can Paul do so? 
Yes, without joinder of any other person in the conveyance.  Yes, if Charles, Sam, and Sam's only child (Gene, aged 25) will join in the conveyance.  No, regardless of who joins in the conveyance, because Sam may have additional children whose interests cannot be defeated.  No, regardless of who joins in the conveyance, because a title acquired by quitclaim deed is impliedly unmerchantable.