Content type within content type? I have such a situation:

I have 4 content types:

city (name)
cinema (name, city_ref, hall_count)
movie (name, description)
session (movie_ref, cinema_ref, hall_number, date_time)

city_ref, movie_ref, cinema_ref are connecting content types with Node Reference module. 

After that with Views and EVA I can aggregate some movie listings, etc. 

What I want to do is to make site content manager register multiple sessions while entering a movie description, i.e.:

there are number of cities and cinemas created and fixed. But the number of movies may change and content creator opens the form and enters name of the movie, description and then has something like multiple sessions: in the same form content admin can enter session, which automatically has reference to this movie, add reference to the cinema, hall number, date AND (if needed) he could ADD additional session with the same duplicated info, but maybe different hall number/cinema and date. 

How could it be solved? Is there any way to connect those content types to make it a bit easier to enter all the data and still have all the relations working?
This sounds like the kind of thing to Node References and the Node Relationships module in D6 or the References module for D7.  Both of those suggest other related modules that might helpful as well.