Took down the chicken wire between the play and dining area and let the two cats roam (while supervised) freely at certain times during the day. Resident Cat (RC) is tolerating New Cat (NC), and NC is learning to keep her distance, but often initiates confrontations.
Both cats simultaneously played with the same toy; NC used RC’s litter box (even though she has her own).
First night letting NC and RC free-roam together; NC made a lot of noise, so we had to confine her to the master bathroom.
First day of leaving RC and NC together unsupervised. In the morning, RC hissed repeatedly at NC when she was let out of the bathroom and RC caught her scent. By the end of the day, both cats were fine.
What used to be stand offs and boundary setting between RC and NC has turned into play. Playtime usually begins with NC chasing RC, or NC batting at RC’s tail. Occasionally play gets a little rough, but never to the point where an adult has to intervene.
Watched a movie, and both cats slept on my wife; they were less than one foot away from each other for approximately two hours. No hissing and no growling from either cat.