You should quarantine the new Chin for 2 weeks. Making sure he is healthy, happy and no longer stressed by the move.
This also give you time to bond.
I call it making him yours before you intoduce him to another chin.
Some chins get along right from the start, others have to learn to like each other, and then some will never ever get along.
I start by letting them sniff each other through a cage. One in my hand and one locked up.
If they seem eager to meet and I see no hostility after a nose to nose sniff I'll let them run together, have baths and see how that goes.
Some can spend weeks side by side in separate cages before they stop being nasty to each other.Then I do the above.
If they don't stop trying to fight you can try the "smoosh" method, not sure on the spelling,
of putting them both in a very small space, like a tube so they don't have the room to fight.
I'm not fussy on doing this, and have only tried it once with a breeding pair, it did work.
I find with only the 2 they would rather have a buddy than be alone.
Give him time to bond with you first though, he'll love you for it.