data entry screen

I am trying to develop a single data entry screen.
The database is sql server and it has about 7 tables which are related.

If 1 record exists in table A, there should be corresponding (may be multiple records) in Table B and Table C ..etc.

I am using ADO.net to access the data. In Visual basic 6.0, I was writing code to populate table B, Table C etc when a record is created in table A. But in ADO.net , I am aware that, we can store the relationships between tables in memory. Is there example code that can demonstrate populating 2 detail tables based on integrity constraints between the master and detail tables?

any suggestions will be helpful.
thanks
nath