Provide the theme summaries for the following conversation: 

David: Guys, as you might already know, Tom won't be able to come with us to the Festival
Olga: What happened?
Fred: Just some work related stuff, don't worry.
David: Still that leaves us with a spare ticket that we won't be able to return
David: So ask around if anyone would like to come with us
Nancy: What about the sleeping arrangements?
David: We still have the rooms booked as before, depending on who'll replace him, we can always rearrange...
Nancy: True
Fred: If I remember Steve was interested when we started planning, maybe we can ask him?
David: Already did, unfortunately he can't...
Olga: I'll ask my brother, he likes that kind of stuff, so he might be interested to come
David: Great, please do
Nancy: What about the rest? They're not here atm
Fred: I'll call them later and ask if they know anyone who would like to come.
David: Great, that way I don't have to do it :P
David: Anyway, we still have some time before the Festival so it's not super urgent
David: but keep that in mind and if anything changes keep each other updated!

Summary: 
Tom can't make it to the Festival so David suggests everyone asks around for someone to replace him. 