My biological mother was dead when I'm still 11 years old. Now I have a stepmother she was married to my father 36 years ago. My question are:

1. Is my stepmother be my legal mother since she was married to my father?

2. Is my stepmother entitled to all benefits granted by our company to all parents of married employees?

With question number 1, were you adopted?

With number 2, yes.

I'm not adopted. Do I need to be adpopted by my real father and my stepmother to qualify her to be my legal mother?

You should be adopted by your stepmother for you to qualify as heir. Otherwise, the legal bond is only between them as a married couple.

The tie between you and your father of course is never dissolved. He is still your father and you need not be adopted.