Today we will be picking up two senior cats (11 and 13 years) that had to be given up by their previous owner.
These two cats are being fed a different brand of dry food than what we give our other cats, and the food is a "senior" formula. Our other cats receive "Light" dry food (only one of them needs "light" food, but since she steals food from the other cats, they all get it).
We will be doing the normal "quarantine" with the new cats, isolating the pair of them in the basement until we can gradually acclimate them to the new environment, and our other cats to them.
I am uncertain how we will approach feeding once the cats start mingling.
I'm reluctant to let our younger cats have access to senior food, and changing from one brand of food to another suddenly worries me (see this answer), but I'm not sure how this can be avoided. At the same time, I'm worried that a change in environment (two, really, since they transitioned from their home, to a pet food store, to our home) coupled with a change of diet will be unnecessarily stressful, particularly for senior cats.
What would be the best feeding solution?
Edit: my apologies, but I left out an important consideration Our cat who needs the light food needs it because she has food issues. Specifically, she was malnourished as a baby, and, as a result, gets very stressed if she does not have food available at all times. Even a nearly-empty food dish will cause her to pace, cry, and beg. So dry food being available 24/7 will likely be a necessity.