How do you change a father's name on a birth certificate in Massachusetts if both mother and incorrectly listed father are dead?

I am the result of an affair of sorts. My mother when separated from my stepfather had a one night stand with my dad. I didn't know my dad until I was 13 and now that both stepfather and mother are passed my dad and I would like to have me be known as his correctly. I don't miss either one and have wanted this forever. But, without they to sign off on this how do we proceed? We're meeting with an attorney soon. But, I'd like an idea of where to go with this.