It depends on what type of chapter you're referring to. There are different rules for the different types of GLOs that must be followed, and procedures differ whether it's for a NPC, NPHC, NIC, academic/professional (like Sigma Alpha or Alpha Sigma Kappa, etc.) and so on.
I can only speak as a member of a NPC group, but there are strict rules which must be followed to bring a new NPC sorority on a campus. Each sorority also has their own extension policy in place. You probably can find many sororities' (and fraternties, for that matter) extension programs on their websites as well. AOII's is listed here,
http://www.alphaomicronpi.org/conten...odayframe.html . Click on 'recruitment', then 'collegiate recruitment', then 'extension.' I also found KKG's extension info on their site,
http://www.kappakappagamma.org/extend.htm .
I'm sure you could also find more info at
http://www.npcwomen.org/.