New kitten fighting with cat and dog... plus other info about Mo

First,
All of you remembered the predicament I had with Mo, and everyone tried to help. The reason for his behavior was a painful hernia, unfortunately during the operation he lost to much intestine and the vet had to put him down , don't realized how quickly you get attached until something like that happens.

The new kitten that the shelter let me have is beautiful all grey with grey eyes and a grey nose (pictures coming), he is very friendly around me, and I have kept him seperated from the other kittens for 2 weeks. He is now 11 weeks old and the other ones are about 16 weeks old.

This weekened I slowly began introducing him to my Parents Westie (so they can babysit, I am aware westies have a high prey drive and I have been very careful), but it seems like my little guy is not to fond of the dog or the other two kittens in the house. The other two kittens are very friendly, when i took him upstairs he was the only one hissing, the other two are significantly bigger. Should I allow them to duke it out? Any adivce?

Thanks guys!

Josh

All the animals involved have been neutered

The kitten's reaction is normal when in new surroundings. In a few days, they will buddies.

The kitten has been here for several weeks, but that is what i figured

Don't forget, he's smaller, and is just establishing his own place (before any of them can attack first!). It may get difficult down the line though, because cats recognize each other by smell, and if he brings a new set of smells with him each time you go over there, or they smell different to him (from home) they may always be 'strange' to each other.