Answers
According to the pertinent provisions of the Greek law, family members who are also eligible for Golden Visa are the direct ascendants of the investor and his/her spouse/partner. Accordingly, your biological parents are the ones who qualify for the Greek Golden Visa application.
As long as your stepfather is married to your mother, I believe that he should be eligible for the visa. Certainly some cases are subject to approval.
I don’t believe you can include your parents or your stepfather at the Golden Visa petition, as you are an adult now and in such case, you may include your husband or wife and minor children.
Your birthfather, except if you were officialy adopted by your stepfather.
Eligible parents for the Greek Golden Visa program are: your birth parents; if you are married, your parents-in-law; and if you are adopted, your steparents.
According the provisions of the law in force, third-country citizens granted for a permanent resident permit for property owners can be accompanied by their family members, who will be granted resident permit privileges too. These family members are considered: spouses, partners through a cohabitation agreement signed in Greece,direct descendants of spouses who are under the age of 21, direct relatives of spouses in the ascending line. Regarding the parents the law, the biological ones are recognized. Family members could either submit their application for an initial residency permit simultaneously with the investor, or they have the option to submit it subsequently whenever they enter the country. The family members are granted a resident permit of the same duration as the applicant. Family members have the same obligation pertaining to the collection of biometric data.
Your birth father.