I would like to explain my situation first before asking my question. A righteous man, whom visits the masjid often, reads Quran, delivers da'awah in person and online, and is well known by many in being a very humble man and has a very clean reputation.
This man has come to ask for my hand in marriage. This man is Palestinian and I am a Yemeni. Many men have come and ask for my hand, coming from very wealthy families but I would discover that they do not pray, and live a very wild lifestyle. My father who is very much absent in my life (I see him maybe 3 times a year, and he lives a few blocks away from me) has accepted the marriage of these men that I do not want because they are Yemeni.
My father has rejected the offer of the Palestinian, simply because he is not Yemeni, and does not care about his religious accomplishments. My father also expects to keep half of the dowry that I receive for himself and has requested that my dowry be 40 thousand. May Allah (swt) have mercy on us.
I live with my mother and stepfather, and everyone but my father agrees to this marriage. I already know that the wali, to have a marriage valid must be parental. My grandfather sadly is a lost man, and wants nothing to do with me, and he is nowhere to be found. May Allah guide him. My uncle has passed away, Allah have mercy on him. I have my brother who is the son of my father and is 20 years old and is considered an adult in Islam.
My question is, with my father's irrational thinking in rejecting this marriage proposal, is this enough of an excuse to have my brother be my wali? And if so, my marriage will be valid in the eyes of Allah, even if my father rejects the proposal?