Mary,

What I've done in the past is stack baby gates in the door way so the cats can sniff and see each other, but are protected. I did that for about 2 weeks and then let them out supervised. I found baby gates at the Salvation Army so they were really cheap. If you have friends who have had little kids, they're likely to have them too. Another thing you can do is, once the baby gates are up, at mealtime, feed them near the door. This will let them have a pleasant experience.

That lady sounds like a real doozie. I'll bet dollars to donuts that they were NOT littermates.