Hi there Anon,

So, you’ll want to gradually create positive interactions for them and make sure you spend one-on-one time with each. It always takes a few weeks for a new puppy to get used to his or her household, but with an already established dog there’s some additional adjustment.

Patricia McConnell has excellent resources on dog training in general, as well as multi-dog households. Some articles of note:

http://www.patriciamcconnell.com/theotherendoftheleash/adopting-a-dog-into-a-multi-dog-household

http://www.patriciamcconnell.com/theotherendoftheleash/introducing-a-new-dog-maggie-and-willie-as-a-case-study

If you can get someone to help you with their interactions that would be idea but if not you may want to have one of them drag a leash so you can separate them easily. Also making sure your older female still has some quiet time of her own until they are used to each other. Remember to take it slow, be patient, and be consistent.