I've been thinking about this recently.
I was a nanny for a family for 4 years and left to have my ds. My youngest charge was 5 months when I started then they had another baby 2 years later. I was extremely close to my charges and their parents but it's now more than 9 years since I left.
I rarely see or hear from them anymore and had decided to stop sending birthday/Christmas cards this year which felt a bit sad.
Then, out of the blue, I got a phone call from mb on the weekend and it was so lovely to hear from her and to hear how the girls are getting on. Now I feel awful that I didn't get in touch on their birthdays but will make an effort to write to them at Christmas.
There are other families who I have childminded for, since ds was born, who we still see regularly but that it largely down to my ds. All my mindees adore him (much more than they like me
) and one ex-mindee put my ds on his family tree as his brother at school and left off his 2 sisters! He has now accepted that my ds isn't actually his brother but has asked that he could be his real cousin.
There are quite a few who I saw a couple of times after finishing with them but contact stopped fairly quickly.
I think a combination of both seeing your dd on her own and seeing you all as a family would be great. I often had my girls over (and their sister who was born just after my ds) to stay when I was still living near them and sometimes worked for them at weekends. It was also really nice being invited over for lunch occasionally.
Sorry for rambling
but I have lots to say on this subject!