Emma barked at DH when they were playing together. He barked, and then so did she
Milli barked in the first hour we had her home-DH brought Emma in (she was at the sitter's while we went to pick up Milli), and immediately Milli growled at her. Emma got closer to check her out and sniff her, and Milli let out one scrappy little bark and scared Emma silly
Now they "talk" to each other all the time-they will even "call" each other from different rooms of the house to come and check out whatever bird or rabbit might be in the yard, or to tell each other to come and play!