Wajib Maintainence of Relatives (draft from lfiqh khutba of Shaikh Ehsan)

Relatives, means parents and children be they male or female.
Others like aunts and uncles is not wajib, it is however mustahab.
If parents and children are capable of providing for themselves, it is not wajib.
For a wife however in every situation it is wajib upon a man to provide for her, no matter if she is a very rich person.
If he (parents, children) can provide for himself using khairaat money such as khums, zakat, sadqa then your responsibility is not removed and it is still wajib

If he can provide for himself by taking a loan, it is not a difficutly for him to take a loan and is able to pay back the loan in future then the wajib responsibility is removed, if any one of the two conditions is not met it becomes wajib to support.

If son takes a loan to study and get a job according to his status and thus would be able to pay the loan at a later date after getting a job, it is still wajib upon the father to spend for his education.
If the son can work but his work is very difficult for him and not appropriate for him it is wajib to provide for him until he finds an appropriate work.

The son is unable to work because he has gone to study Islamic studies or has gone for jihad it is wajib upon the father to provide for him.

The son does not work because hes lazy despite being able it is not wajib upon the father to provide him