I have 2 content types:
Organisation (Name, address, tel, places)
Internship (Reference to Organisation , Student, Mentor, ...)
Now for example I have an organisation with 2 places for students. So when this organisation is selected as a refernce in Internship node creation, it must check for the available places. If the pace is available then it needs to save the node else it should give an error message.
I have tried node limit module but it is not a solution.