Yes! Make now has a native solution for exactly this! 
When you need to recombine two or more branches into a single flow, use the new If-else & Merge modules instead of a router.
These two new modules let you branch your logic, handle each path independently, and merge the results before passing data to a single module (like your Mailchimp).
More details here: 🔥 Feature Spotlight: If-else & Merge in Make is here! 🔀
Happy automating! 
Valery from Make