Yes they can "share" etc (I have been teaching my friend's 2 yo who I babysit). The day that I work, I leave DS with my friend (the one whose daughter I mind - we do a swap). I agree that kids love to be around other kids - my DS loves the day that Simone comes over, or that he goes over to her place.

But, I don't agree that sending them to childcare is the way to do this. What about playgroup or Mums' group? We go to both - so DS can interact with other kids, but not be left without me. I don't want my DS to be looked after by strangers at his age. For better or for worse, his parenting will be a reflection of me - not CC.
I did all these things too It wasn't until the last week that I have sent them to any sort of child care.
I wouldn't call FDC a stranger though. They are no more a stranger then your friend once was One carer which they get to know and build a relationship with. We even visited a couple of times to get the boys used to her and get to know her a bit better. I wouldn't call her a stranger anymore.