I'm coming to this thread rather late but had to post as I was about to start a thread of my own on this subject. I know exactly how you are feeling.
I lost my lovely mum 9 years ago, very suddenly. She had 4 grown up children. I am the youngest, I was 26 when she died. She never had the pleasure of being a grandmother. Since then, she has had 5 grandchildren, none of whom will ever know her. One of these is my own one yr old DD.
Having my DD has brought back some of the rawness of my early grief for mum. There are so many things I would have liked to ask her, about babies, breast feeding, nappies, sleep etc. Much more than this though, is the overwhelming desire to see my mum and my DD together, playing, cuddling, laughing, enjoying each other.
I have a fantasy, that mum comes back just for one day. She comes to my house and we spend a whole day together, the three of us, me, DD and mum. We have breakfast and then playtime. I watch mum read a book to DD; encourage her to walk; teach her a new word. Then we go out for a walk and DD sleeps in the pram and me and mum talk - really talk- and I get to ask all my questions. Later we have lunch, then more playtime in the afternoon, maybe doing some baking; singing songs; lots of cuddles. After tea, mum helps with bath and bedtime, and reads DD a bedtime story ( as she did for me every night for 12 or so years). Then the hard part- The end of the day and having to say goodbye to mum. As I never had a chance to say goodbye when she died, this would be very painful but also very wonderful, and the pain of parting would be well worth the joy of having her here for just one day.
I'm not sure if my fantasy is a good thing or not- it always makes me cry. But it makes me happy too, to imagine my mum and my DD together, as if it were almost possible.