I have an upcoming international flight where I have a paid ticket in Business class. I have United 1K and have status. I bought my brothers two separate tickets as well. One brother I bought an economy ticket and applied a GPU which cleared. The other brother I used my frequent flier miles to get him an economy plus ticket. When I pre-board for this flight, are my two brothers allowed to pre-board with me since we are traveling together? Or do they have to wait till Group 1 or later, depending on whatever is written on their ticket? Thanks!