I have some friends there right now (either in Prickly or Clarke's Court Bay). They have an 8 or 9 year old and a newborn (born whilst cruising!) I can put you in touch with them if you like.
We found the best way to hook up with kid boats in the Caribbean was to follow the popular routes for cruisers and, in particular, the Caribbean1500 rally was a great way to build a cruising kid network.
We had about 8 boats that we buddy boated with off and on for the whole season, but occasionally we'd run into a family
where we were the first kid boat they had encountered. Those folks tended to be Europeans who had come across and started there Caribbean cruise
in St. Lucia (or further south) and then headed north.
By contrast, most of the folks we sailed with went straight to the BVI's in November (most of us on the Carib1500) and then we cruised the leewards and windwards.