I sent an inquiry through a "contact us" link on UPS' website and received the following answer in the form of an email with "UPS Relative Policy" in the subject line;
Yes, we do have a relative policy for crewmembers. The only relative you can have working at UPS is a cousin. All other relatives working here would keep you from employment. I hope this answered your question. Thank you for your interest in UPS.
UPS Flight Employment Team
oh well, years of aspiring to fly a brown tailed airplane down the tubes