My sister, who lives in DEN, is getting married in SFO this summer. When she had her dress tailored today, they said that she couldn't put it in a suitcase and that she would have to hang it on the plane upright somehow.

She's flying DEN-SFO in Y. What are her options in taking care of her dress? Is UA accommodating to this, or would it be best to try to upgrade her to F? She's flying with my mom, who is a 2P, but it's impossible for 2Ps to upgrade on that route, so should she fork over some miles/cash to ensure that her dress is hung somewhere and makes the flight safely?