You can add any guest or visitor to your room as a friend in Here's mobile app. To do so, follow these steps,
- Enter a room with the user you want to add as a friend
- Click on the Members List next to your profile in the top right of the room
- If your visitor is present in the room, they'll appear under Here. If they're not present in the room, they'll appear under Not Here
- Tap on the guest you want to add as a friend to bring up their profile
- Then select Add Friend
