That's sweet anyhow because the 2 cats u have ,have been together for so long they might not accept mimi but maybe after a month or so they will accept her So I think it would be great to foster mimi don't worry and don't forse the 2 cats to accept her at first it will take some time but after...
Don't worry it does not cause death but very discomfort for the kitten.My kitten Minnie had it for a while we took her to the vet she wasn't mush help so we gave her meddacine 2 times a day and soon after we got it back.Your kitten most likely had a pease of food that went down the wrong tube...