Scary Mary is a brave and rather pretty lady. She's been through it though; I think she'll hang in there. It appears that she wants to be a part of the clan. Shock and outrage is frequently the first reaction by the territory holders; hurling himself at the screen, however is not a great way to introduce yourself, Dex. Perhaps, if you feed Mary on the landing, and put a soft napping place for her and a water bowl there, and let this be the introduction for several days, everybody will get a chance to see her and will observe that the humans have deemed her worthy of companionship, and understand that she is to be accepted as a new cat clan member. It took a couple of weeks before my 4 year old male accepted the new 6 month old male, but I didn't rush it either. Now, they're fine together. Big relief. Just wait and see what happens. It may not be quick, but it will most likely be eventual.