Is it permissible for a full brother to marry off his virgin sister if their father refuses to marry her off for illegitimate reasons?

If a qualified suitor proposes to a girl, her guardian is not permitted to prevent her marriage to him without a legitimate Shar'i reason. Should he do so, he is considered to be coercing her. In this situation, the guardianship transfers to the next closest guardian according to the Hanbalis (madhhab), or to the ruler (Sultan) according to some scholars. It is preferable to refer the matter to the Shari'ah judge for consideration.