If you are currently investigating moving your shared mailboxes or public folders into Office 365 Groups, a recent MigrationWiz update by BitTitan could help you. You can now select Office 365 Groups as your destination mailbox in the product. This will allow you to move from any other supported mail system into Groups, including existing Office 365 Shared Mailboxes.
I hope to write an end to end blog post on how to complete this migration soon!
To take a look at the functionality yourself visit http://www.BitTitan.com. If you have any questions or comments please either use the comments section below, Tweet me @MikeParker365 or via email firstname.lastname@example.org.