Steps to reproduce:

1. install 6.0;
2. create parent Service;
3. edit new parent Service and try to add new Child - button is not working;
4. close edit, go into parent service, press Create service;
5. open Child tab, add button is working and it show parent service as a child to be added;

Result:

Expected:
Add button working.
Child service should not be able to add parent as it's own child.

Looks confusing.