Form the 2004 safety code (I believe this was added for 2003):

5) I will not knowingly operate my model within three miles of any pre-existing flying site except in accordance with the frequency sharing agreement listed below in this paragraph.
Flying sites separated by three miles or more are considered safe from site-to site interference, even when both sites use the same frequencies. Any circumstances under three
miles separation require a frequency management arrangement which may be either an allocation of specific frequencies for each site or testing to determine that freedom from
interference exists. Allocation plans or interference test reports shall be signed by the parties involved and provided toAMA Headquarters. Documents of agreement and reports may
exist between (1) two or moreAMA Chartered Clubs, (2)AMA clubs and individualAMA members not associated withAMA Clubs, or (3) two or more individual AMAmembers,
Document Number 551*.


Looks like if you can't sort something out with the other club then you'll need to get the AMA to step in....