Unfortunately there is no way to do this.
I need to do that same with vantage and classipress.
But because the themes are their own theme and style set with functions the best way to do it would be:
Create a WP
Multisite for the main wordpress install
then install a sub site and install vantage
install another sub site and install classipress
Then pay a developer to create matching child themes for your vantage and classipress sites to match your main site.