Hiya,
We have a 10 month old Lab called Oscar and when he was 6 months old we got 2 kittens (also then 6 months old) from a local rescue centre.
Oscar has always been very 'enthusiastic' with the cats, and at the beginning we thought he would never calm down - but gradually over time it got much much better.
I think its probably a learning process for the cats at much as the dog about how they need to react to the other to get along without too much stress.
We introuduced them very gradually at first and always in the house when we were around. And then as Oscar probably got used to them being around and knew that he didn't have to play with them at every oppourtunity, we let them out in the garden together. In the garden we had to start again letting them play together gradually, as with all the space out there, again Oscar began to chase them round like mad.. but as with indoors over time this got better and better.
Now it is very rare that he even gets up when they come in the room, and during the day they spend most of the day sleeping in the same room and quite often in his bed all together.
One thing I think that worked when we first got them more than anything though, was giving them treats together. If there is something that they all adore, ie small pieces of chicken or ham (Oscar is a typical labrador and everything is his favourite, but the cats are a bit more fussy!) try getting them all together to treat them. This way Oscar was completely distracted by the food and chasing the cats didn't even cross his mind. It allowed them all to get very close together, and Osc got used to sitting calming when they were around (he didn't get the treat unless he did what he was told).
I think really though, as I said, it's time that helps. The cats will soon suss out how they need to react around him to least get a reaction. If our cats don't want to play, they creep past him very slowly so as not to get him excited. And if he wants a game, he jumps around a little way away from them working out whether they are up for it or not.
Good luck with everything and I hope Bonnie settles in really well with her two new sisters.
Sarah x