we also have a coffee meet-up on Wednesday afternoons in Pok fu Lam...there seems to be quite a few twin mum's in the area so thought we would (you should see the look on people's faces when we all attend with our babies!). If you wanted to make the effort to come along, you are more than welcome. I sometimes take my 2 year old son along also (who am sure would love your boys). There is also another mum who attends who has a 2 yo son (plus, the twin babies), so could potentially be a good playdate for them.
Pok fu Lam is about 15 mins cab ride from central....unless ferry's from Cheung Chau come into Aberdeen, in which case is very near.