fundraising plugin, paypal ipn setup

ok, i am trying to set up a site that many people can fundraiser for adoption as well as other charities. I want to use your fundraising plugin, but I think i may have hit a snag with its designed use. According to your settings the user must use their subdomain.chainsremoved.com/***-*******-******/paypal/ as their IPN on paypal. That is great if each user uses their own paypal account. However, I want to set it up for my partner 501(c) organization so donors can have a tax deductible donation.

Can you advice if I use the main domain (chainsremoved.com/***-*******-******/paypal/) as the IPN if it will work on all sites that want to use the 501(c) org or if I can create one subdomain site that each site can use say plug in 501c.chainsremoved.com/****/paypal and just have the organization use that or will paypal never receive the payment if they don't have individualized ones.