The moderator (creator) of the room can add members to the room. The mod can also appoint other members as moderators to do the same.

Adding a contact to a room or 1:1 message is very simple and works the same way on every client.

 

Adding a contact to a room 

  • To add a contact to a room simply click on their name within the "Edit Room" contact list. This assumes the user is currently within your network.
  • To add a contact from another network to a room, enter their email address in the search field. If the user is valid and active on another network, they'll be added to your contact list allowing you to add them like any other user.

Creating a new 1:1 message 

  • Clicking the "+" symbol next to "/ Conversations" on the left brings up your contact list, allowing you to choose a person to begin messaging.
  • If the user isn't currently in your contact list, you'll need to enter their name in the search box, and then add them as a contact. You're only able to add valid and existing users, and not invite using this field.

https://support.wickr.com/hc/en-us/articles/115007397628-How-Do-I-Add-a-Contact-to-a-Room-