The old adage, it is easier to ask forgiveness than permission seems to be the rule here.
What we know (at least what I have read and understood) is that the majority of GG's would rather you tell them early in the relationship than after...oh 20 years. Why? Because things get comfortable. You have routines. You have families, soccer practice, PTA meetings, friends and neighbors. This turns all that upside down.
I am going to say that I don't need to know every detail of my SO's life before we got together. For that matter I really don't need to know every detail of what they do today (OMG did she have wine with lunch????). But somethings have a bearing on the structure of the family. And you , as CD's (TG's TS's DQ's or other initials) know this. Yet you hide things because why? YOU are afraid. No consideration for anyone else, just YOU are afraid. You are afraid you will lose what you have, a partner who stands by you, who comforts you, who shares almost everything with you except your secret. How nice.
So I guess what I am doing here is preaching to the choir again. Those of you who came "out" early know that things work out better. Those of you who are still hiding. what are you gaining? You know (in your heart you know) that when you get caught things will be worse. So why are you waiting?