I think you're an excellent mommie to Simba and Nala and would make a great mom to a cat, BUT for now I think I have to agree wit PIF in that a permanant outdoor enclosure is not the best idea. I think it might be a little unfair to keep the cat outside because Simba does not like cats. It's an unfair and preventable stress on Simba, the cat and you. Again, just my opinion.

Not to say that something could not be arranged, espescially when you are such a commited pet parent. On the flip side I think getting Simba used to Orion and Caleigh first is an excellent idea before you commit to a new cat. Simba can more than likely grow to love or at least tolerate a new cat where you wouldn't have to keep him or her outside.

An outdoor enclosure is a great idea if you could proide one, but I think it should be used for play time, and outside time, not as the cat's home. Maybe at first it can be the cat's home, until Simba can tolerate the cat, but definitely not for the long term. I think it would take a lot of commitment and patient to integrate the situation so everyone can live inside, but I'm sure you're the kind of person who could make that happen.

Good Luck and keep us posted.