Relatives under Rule 4 of companies(specification of defination details)Rules,2014 daughter does not include step daughter according to the defination given under relatives
Father, mother, son, brother and sister include the step-counterparts but there is no specific mention about step-daughter. It may be a drafting mistake or may be an intentional exclusion. Whatever it may be, but the plain interpretation of the section indicates that step daughter is not a relative.
We get one more surprising thing here. In one case, a person can be relative of another in one way, but the reverse way, the person is not a relative. For example, Mr. A has a step daughter Ms. B. So for Ms. B, Mr. A, being a step-father, is a relative. However, for Mr. A, Ms. B is not a relative as step-daughter is not a relative.