Inadvertently, two times in the past few days Mika's door got opened and she was able to visit Tasha unrestrained. She made some low yowling (not really growling) noises and kept her legs straight and head up while she looked at Tasha, but did not try to fight. Tasha knows how to keep her eyes diverted and her head down to avoid confrontation so this helped too.
Today, after this happened again we decided to let them both loose in the back yard in the hope they could get along together without being separated. It seemed to work great and we hope it will continue in the future. Mika seems to want to play with Tasha, but quite obviously wants to be the dominant player. Our old malamute Shasta who passed away a year ago also had this same "I'm the dominant one" attitude and this did not make her popular with all dogs. Tasha, who loves to play with most dogs just can't seem to get comfortable with this new big dog and just averts her eyes and head and stays still. Mika will even grab Tasha's neck fur on top to try to get a reaction, but Tasha won't respond. At least we are pleased that they can be together without fighting.