As I understand it, "friends" refers to the following people:
Horn
Porizatel
Lord Maniac
Also, please clarify the dates of their stay...
That's correct, Lord didn't buy return tickets, according to my information.
Horn leaves on the night of May 4th to 5th. Porizatel and I leave on the night of May 6th to 7th.
P.S. Please add the arrival dates for all 4 of them in the first post.