In our next Yonkers' co-op election we are trying to avoid questions about signature veracity on proxies by asking residents to bring their proxies to a lobby registration desk with proof of identity and signature...passport, drivers' license, etc. Can we make this a request or a mandatory condition?
In my experience the co-op boards always have a lawyer they turn to for these types of questions. This isn't my area of practice so I can't help you.
Good luck.