getting a bid

If your sister is in a chapter, you're considered a legacy and get special consideration. That doesn't necessarily guarantee a bid, and legacy rules/traditions vary by chapter. Consider it an advantage, not a promise.

The majority of siblings who rush at WashU join their legacy chapters, but not all. In the end, it's more important to find the right fit for your personality, goals, etc. And don't rule in or out a chapter based only on how similar you think you are to the person you know in it, be it a friend, sister, or otherwise.

No other PNM has the official power to get herself, much less, you a bid. She can, however, put in a good word for you, and it certainly helps if you've met older chapter members through her. Same goes for if you're the legacy: the best advantages are good word of mouth and the chance to have met more sisters who can vote in your favor.