genorb:
I know it is possible because I received some messages of this kind from Zagraniczniak. But I don't know how to do it. Zag can probably explain to us if he reads this.
Regards
First, you need to be friends. Then I go to one of the friend's profiles and click the button at the top that says "send a message". The new message box will appear with that friend's name in the recipient line (in a box, with a red X).
Click next to that person's name and another small box will appear. Start typing the name of another friend. The program will offer to 'auto-complete' the name, for example if I type a Y, I will get a list of friends starting with Y, if I then make it Ya I will probably get just Yankee Jim. Move down to click the name you want. Click again in the recipient box to add another name. etc.
If you change your mind and want to delete the person from the original list of recipients before you send the message, click the red X next to that person's name.
When the message is complete, click 'start the conversation'.
Then when people reply to the message, it will automatically go to everyone in the list. A thread of messages is formed in this way. I did not find a way to remove someone from the thread. Instead, I had to start a new thread of messages without that person.
I seem to recall that once the thread is created, everyone will get the messages going back and forth even if they are not all friends with one another, but were only friends with the original sender.