You can detach / de-link the child system before an upgrade or other such activities and link it back once completed.
Use the report RSDELCUA
After reconnecting you would need to transfer all the users back to the CUA.
Remember to have the CUA / Sol Manager at a higher version than the child systems.
When you de-link the CUA, you can administer the child systems individually.
Good Luck.
Goutham