How do I introduce a Chihuahua puppy into a home with?

I would suggest that you take all the dogs on to mutual grounds, don't take the new pup in to the house because that's their home. Take them to the park and introduce the dogs all together. At the same time give treats to praise them all, as they sniff treat ten etc, they will then link the new dog to new treats. Then walk them all home together and take them in. Always reward good behaviour. Hope this helps.