Sending campaign to multiple lists

@dtommy79 - Though please think twice before doing that... we don't advise it anymore and most likely that feature will be removed from the app in the near future.
Curious on how this works. I have "Send to Multiple Lists" as a Yes in the backend, but when I create a campaign the list selection is just a drop down. I don't see how I can select multiple lists. What am I missing?

BTW this can be very useful so don't get rid of it :) Lets say a retail client has multiple locations so they have multiple lists (one for each location) Some emails are targeted to one location but others may be going to multiple locations so Ideally I'd like to select the lists and then MW would filter out duplicates in the background for me.

Excellent! Thank You! I missed the big "Add new list..." button o_O

Without testing myself does anyone know if duplicates are taken out during the sending process?