Last night was encouraging. My niece and I talked about it and she is going to try my tactic of simply putting a hand down and saying "uh-uh" or "no" to get him to stop with the dog. He started to go for the dog and I picked him up and talked to him calmly and gently and stroked his head and he snapped right out of it. Meghan is going to try that, too but I asked her to be careful the first couple of times because he obviously doesn't trust her as much as he trusts me.
We have also physically blocked off the livingroom from the rest of the apartment so I know for sure that while we're gone the dog isn't sneaking back there and harrassing them. I have 2 litter boxes and they are both in this back area so the dog definitely can't keep them away from it. Unfortunately I don't have a yard as I live in an apartment on a busy street but we take the dog out for short walks to do her business several times a day. My niece also spends weekends at her boyfriend's house so they get a break from the dog for a couple of days a week.   
I have always kept boxes around the house for them to hide in and the dog is absolutely NOT allowed on my bed as this is a most favorite napping spot for all three cats.
I had a small spray bottle of Feliway that is almost empty but I tried it and it seems to have help so I'll be going out to purchase a diffuser next payday.
All in all, things are looking up.