How do I configure read write access for users to have rw access to three repositories and no access to the parent or other repositories?

Setup the three repositories, then modify the svn_access_file to allow specific users rw access to the repository and no access to the parent and the other repositories.

The required configuration is seen in the following code sample:

ls /var/svn/repositories/
repoA repoB repoC

more /etc/opt/CollabNet_Subversion/conf/svn_access_file (1)
[repoC:/]
user1c = rw
user2c = rw
user3c = rw

[repoB:/]
user1b = rw
user2b = rw
user3b = rw

[repoA:/]
user1a = rw
user2a = rw
user3a = rw

[/]
user1a =
user2a =
user3a =
user1b =
user2b =
user3b =
user1c =
user2c =
user3c =

[groups]
group1 = user1a, user1b, user1c, user2a, user2b, user2c, user3a, user3b, user3c