Problems branding new pages in Multisite

I have installed this plugin in my site and it works great on the main site. But I would like to be able to change some of the branding for each new site I create in Multisite (ex. the login logo). Each new site carries the logo from my company, but I would like to specify a new logo for each new site.

How can I do this. I don’t know if I can do this with this plugin or maybe I have to edit a core file. Let me know pls. Thanks