suicide ranking?

Yeah they give priority to girls who ranked all of their houses

who told you that? That's not how it works. Panel can't dictate what pnms a chapter takes unless they don't meet a gpa or are in trouble with the university or something.
If you suicide you eliminate your chances of being made a quota addition to whichever chapters you have left on your pref card.
A quota addition is when a pnm maximizes their options, isn't matched with either of the houses she has left, and is then added to one of their quotas. No one know she's a quota addition, she enjoys bid day and gets her bid the same as everyone else.
So ilets say a pnm has sorority A and sorority B left at pref, and she ranks both on her card as 1.A 2.B, and quota is say 50. Sorority A has their ideal pledge class of pnms ranked 1-50, and our pnm is number 51 on that list. She didn't make sorority Bs top 50 either. So she is added to the quota of sorority A.
Now if our pnm had suicided and only rank A on her prefer card, she would be ineligible to be added as a QA to sorority A!! So she really screwed herself out of her favorite sorority.

Panhels goal is to match as many women as possible with a chapter so I doubt they'd make it harder for PNMs to get matched. We already had 25% of PNMs who started the process drop out I don't think they'd want to widen that margin.