How long?

Ive been in a relationship for 18 mths now to a wonderful man! I have fallen head over heels with him and he means everything to me. But there is a but............ I am not allowed to meet his 9 year old daughter and havent met any of his family yet. Have met some of his friends though. He has a big issue with his family and has told me that even though he wants a future with me he not sure he ever wants me to meet his family! What do I do? He has met every family member on my side apart from my 2 youngest who are both 17 years old! Reason being my daughter is a nightmare she upsets me a lot, my son is just so laid back and couldnt give a damn about what I do basically. Help!