national chapters vs local chapters

[Panhellpres]

Our school has an established PHC and IFC organization on campus. The two groups work together all the time and each sorority and fraternity has a house in the area. Our school just recently formed a multicultural greek council for all the culturally based councils (including NPHC.) Our problem now is that our sororities and fraternities aren't willing to accept the multicultural greek council yet. The reasoning is because both IFC and PHC groups have GPA requirements, as well as a Greek Life plan with other mandates like risk management programs.
The multicultural greeks are a little wary of the PHC/IFC groups because we are so established and already have so much support from the university. But I do know, they are interested in being a part of Greek Week and other programs that we put on.
Do other schools have this problem? How do they handle it?