Every way to add contacts in LiveHive gives you the opportunity to add those contacts to an existing group.
Manually Add a Contact
When you add a new contact individually, you can add a contact to a group right away.
When you click the Save Contact button, the contact will be added to all of your contacts, and the selected group.
Upload a CSV File or Import a CRM List
If you upload a CSV File or Import from a CRM List, you're given the option to add the new contacts to a new group or an existing group.