They were always going to be permanent additions. We have enough room that H.S. could live on another floor. I wouldn't have put her in that situation if we were in a condo. She wasn't restricted; she had free rein of the whole house; the kittens were cloistered to the upstairs via baby gate. And while they were kittens and rambunctious, they were getting put to bed in their own bedroom, not allowed to sleep with us. I.e. the calico would take advantage of that and get her snuggles in at night (as well as on & off throughout the day as we both WFH).

We did become their fosters when they got unfortunately early weaned, as we had put in adoption applications on them when they were 2 weeks. We got them at 5 weeks. I fed them a wet food/formula slurry and monitored their weights, got them that stuffed cat surrogate that has a heartbeat, etc. And basically I hedged and adopted 2 instead of only 1 in case the calico didnt like them, they would have each other.