My mom asked my genderqueer sibling to do a mother daughter fashion show with her?

I have a fraternal twin, who is genderqueer or transsexual i'm not sure. She was born male but I guess the world is presents as female or lives as female everyone most of the time refers to her in the female sense so I would say she is transsexual but she refers to herself as genderqueer. My mom favors her over me, like they always going shopping together and yes she'll buy me stuff but she never invites me to come along. The few times we do go out she gives my sister all the attention, she pick stuff out for her to try on and she'll comment on it she doesn't do that for me. They spend tons of time together and she never even ask me if I want to go, my sister will but she won't. Now one of the groups my mom is a part of is doing a charity mother daughter fashion show and she is doing with my sister, she didn't even ask me if I would want to do it. Should I say something to her? I mean why can't she ever just pick me first or ask me to do something with her? I try not to let it get to me but it hurts.