lived across road for a few years and never really met them except once saw mum in the shop and she said hi. i never realised they had another baby (they have older children) but saw a toddler today - they must have not been out at all much the last couple of years because i am out and about multiple times each day and have not seen them or this baby once, i don't think they have been away but you never know. should i knock the door (i have a 3 year old) and invite the mum for coffee and play (incase she has been locked away with PND or something) or would that just be totally weird since they don't know me at all.