The first thing to do is to fix some of the broken links on your school's Greek life page.

I would also advise that APO and GSS not be included in IFC or Panhel (if they are already) as these groups choose their members in a different way than IFC or Panhellenic groups. APO chapters (I won't speak for GSS) are really not supposed to be in IFC or Panhel.
As for supporting your nearby chapter, one of the best things you can do is for each chapter sister (or a few of them since the other chapter's numbers are quite low) to "adopt" one of the girls and send them daily notes of encouragement, hellos, etc...basically just reminding them how lucky they are that they joined the group that they did. If it's at all feasible, travel to their campus for Homecoming, Greek week, other events etc and WEAR LETTERS. Offer to let them "practice" on your guys to improve their conversation skills for rush and to find quick ways to get out of sticky situations. (Pretending to be the rushee who won't talk about anything except Twilight is always fun.

)
I won't say attend their rush parties, unless you stay in the background as many PNMs on here have stated that they really disliked talking to a sister all night and then finding out she wasn't from that chapter. Help them set up and such, but when it comes to actually meeting the rushees they need to do that themselves.