NO. Promotion to scale 1 before 40 define privilege class. In your case, income is considerable factor and crossing upper limit. .

Salary and agriculture income is exempted of class 3 and 4 employees which you are not. Appointed in which class has no relevance.

your son would not be eligible for OBC NL as you promoted to class 1 officer before age of 40 

Your son  is not eligible for OBC NL 

Please quote the link if advise you something like this.

Yes he will be eligible

1) the Madras HC had ruled that if salary of

.. parents employed in government is not a criteria for assessi .. assessing “creamy layer”, the salary of a PSU employee “as a .. as a test for identifying creamy layer brings in the element of discrimination 

hence your parents salary is immaterial in deterring OBC NL certificate . Only status is to be considered and not income 

2) Junior management grade scale-1 and above of public sector banks, financial institutions and public sector insurance corporations will be treated as equivalent to group 'A' in the government and considered as 'creamy layer'.

Since you have become a class I officer  before completion of 40 years of age, I am afraid your son may not be eligible for OBC NCL category reservation.

Even though you were recruited as clerk, since your have become a class I officer before completion of 40 years of age you may not become eligible for the said concession.

The rule is that a person becoming a class I officer before 40 years of age may not be eligible for this concession.

1. As per the information mentioned in the present query, makes it clear that you were appointed as clerk and now have become the manager.
2. If this is the case of rejection for NCL then no one from the family of government department would be able to get the NCL benefit.
3. Your son is eligible as per law of determining the NCL eligibility, and same can be discussed in detail.