A: Who is
more entitled to be a woman's Waliy (a legally accountable person acting for a woman regarding marriage) in marriage
if she has no father or grandfather, but she only has a brother and a half-brother?
If the situation is as you mentioned, that the woman has neither a father nor a grandfather, and that she has a brother and a half-brother, then her brother is more entitled to be her Waliy than her half-brother, if he has the legal capacity to be so, since he is nearer to her. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.