If the school is very open for expansion, maybe the advisor should send notice to NPC, so all NPC sororities will have notice and be aware of the expansion opportunity!
(I realize that there are two groups you are trying to avoid because the other locals used to be them)
I definately agree with AchtungBaby that it doesn't hurt to try to get a "big name" sorority on your campus to colonize you, but like they say to everyone going through recruitment -- keep an open mind!
There are 24 amazing groups, and each one, no matter how big or small, is something special! So in the end it isn't about being part of a "big name" sorority, but what the sorority itself means to you and your sisters
Continued best wishes to you & your sisters!