What is the relationship between the characters in Act One of An Inspector Calls?

This excellent play focuses on one family and its various
members. The Birling family are all introduced in the first act as the curtain opens. We
are told that the head of the family is Arthur Birling who is a manufacturer. His wife,
Sybil is a socialite and appears to be a rather "cold" woman. Then, they have two
children, Sheila, their beautiful daughter, and Eric, their shy son. Lastly, they have a
guest with them, who is Sheila's fiancé, Gerald Croft, who is the heir to a business
fortune. Although she is not precisely a member of the family, there is also the maid,
Edna, who is busying herself with clearing the table and laying out port and cigars as
the play begins. It is of course the way in which each of these individuals has been
involved in the downfall of Eva Smith that Goole exposes, forcing them, albeit briefly,
to take a look at themselves and their actions tothose less fortunate than
themselves.