What is the ruling on a sister marrying a young man she met via Facebook, despite her brother's rejection, given that this is considered evidence of his poor morals?

The entry of young people into mixed-gender websites on the internet is a gateway to tribulation and corruption, and the matter worsens when a girl posts her picture. You must advise your sister and explain the corrupting influences of such websites. As for the young man who proposed marriage, although marriage via the internet is fraught with risks, this does not prevent accepting someone who proposes through it. We advise inquiring about this person, and if you are pleased with his religion and character, then accept him. The scholars differ regarding who marries off a woman in the absence of her father: is it the grandfather or the brother? The preponderant opinion is that the grandfather has a greater right to guardianship, though some say the brother, and others say they are equal.