My oldest nephew's dad has never met him. My sister put together a small little photo album of pictures she had of my nephew's father.

She showed him the album when he started asking about his dad.(around 4 years old) She never told my nephew anything negative about his father but did give age appropriate answers as to why he wasn't around.

That was good enough for my nephew and satisfied his curiosity. He always knew his dad's name and what he looked like, and always knew he could ask us anything he wanted to know about his bio dad and we would give age appropriate answers.

My sister met her husband when my nephew was 10 and my nephew considers my brother in law his dad. (My husband has also been a father figure to my nephew and has been around since he was 5)

My nephew is 18 now and is a well adjusted young man.