After taking a peek into Divi's Mailchimp PHP it appears there is no support for this client side classification option in Bloom. Groups are for Users to choose classification - Tags are for Clients to choose classifications and without them, Bloom is unable to provide and support a significant part of Mailchimps features. Creating a group for something like 'signed up at London Expo' works as a group - but its just plain wrong to do it that way and ultimately users can edit their Groups. If ET don’t update Bloom to support TAGS (I don’t expect they will) this could be a significant USP for Divi Engines Form Builder.