1.  Log into Main Parent account
2.  Go to Control > Administration > Organization Setup > Manage Users
3.  Click New
4.  Add Contact information and create username
5.  Save
6.  Click on the "Change Account" hyperlink in the top right
7.  Click on one of the child accounts
8.  Go to Control > Administration > Organization Setup > Manage Users
9.  Click New
10.  Click on the hyperlink for "Search for Existing Account Contact" next to login name
11.  Click radio button next to Sphere user name
12.  Enter additional required contact fields
13.  Save
14.  Repeat steps 6 - 13 for each child account