introducing new puppy to mean dog

Question
I have a six year old chihuahua and a 12 year old toy fox terrier and have recently rescued an 8 week old poodle terrier mix. We introduced them in the yard, my toy fox terrier gets a long very well with the puppy but my chihuahua is still very aggresive towards the puppy and I am afraid that she will seriously hurt her if they are both down.  I've only had the puppy for about 3 days so will it just take time for the chihuahua to come around or should I reintroduce them and if so how?

Answer
Thank you for your question Sam.
I would say the best way to make introductions with new dogs is on nuetral ground. Say a dog park. Keep them on-leash, and watch carefully for signs they are becoming aggitated. When they are at home keep them on leash when interracting. If at anytime, one becomes aggitated, remove the aggressor.
Feed the two older dogs before the puppy. Take them out first. Pet them first. Ect.
Praise any good behavior. This includes ignoring, playing, sniffing, and generally being nice.
Ignore the bad(other than the remving from the situation of course). Otherwise ignore it. Give the dog time away to cool off.
You have older dogs, and your new puppy is very energetic. Do not leave them alone together, even if they seem to egt along, unless you know this for sure.

I wish you good luck. I hope I've helped. And congrats on your new pup.
Emily