Thank you all for those careful and perceptive replies to my post. I'm sorry to have been a bit slow in responding (anniversary of daughter's death).
Reading all your posts, I realised what I should have thought of before: that everyone is different. I experienced some problems over Christmas that left me feeling bewildered and needing advice. I'm divorced, so there is no one to share this with day to day.
Overall, I get on well with the family in question, am welcomed to their house, and the children and I communicate easily. That's what's important, and besides I don't and can't know the background to my DS and DDiL's everyday exchanges.
I am a chronic worrier. Just writing my post and reading your replies has put things into perspective, so I don't now feel the need to be more specific.
Thank you all.
Estranged Son and Future Granddaughter
To think that London, or anywhere else for that matter, does not belong to any one demographic