You can now use a dot in the email alias. We are working on providing the ability to edit the email address of a group after creation.
For the ability to edit the email addresses, we now have the following roadmap item: https://products.office.com/en-US/business/office-365-roadmap?filters=&freeformsearch=27891&featureid=27891
An error occurred while saving the commentJens Jensen commented
Please allow managing aliases to groups through UI. Editing through Exchange powershell is cumbersome, and I understand they might not show up in the UI.