So, here's the setup:
WordPress MultiSite is installed on domain.com.
Multi-Domains is installed.
multi1.com, multi2.com, and multi3.com are, as the names imply, added to domain.com via the Multi-Domains plugin.
Is it then possible to have different sites up on the root of multi1.com, multi2.com, and multi3.com? If an attempt is made to map a domain to multi1.com (via Domain Mapping), a "domain exists" error will be encountered. At present, the domains added via Multi-Domains all redirect to domain.com.
Short version: Is it possible to have different root sites for each domain in a Multi-Domains setup?