"I'll have to ask mum. Or Jun." Cedric was still very much learning, and he really had no idea when Cathy would be old enough for kittens. Helen Diggory would certainly know, since she'd had both kittens and children herself, and there'd been at least some overlap. Jun might also know, since she seemed to be much more knowledgeable on this sort of topic than Cedric was. (Possibly she'd read some books, Cedric wasn't assuming she knew these things instinctively.)
Cedric frowned, just a little. "I think the two of you together sound great," he said, quite honestly. He really had no qualms that they might not get on. It was only the memories that made him feel a slight concern. He sat quietly while he thought it out. If Bill and Fleur had been together, and happy, in some different time line - why shouldn't that mean they could be together and happy in this one? After all, they were still the same people, even if shaped by different experiences. "I'm glad something happy came out of it," he added, after a lengthy pause. He didn't apologise for not saying something sooner - Fleur knew him well enough to know he could be quiet at times. "It makes me feel better for being fascinated by the whole thing," he added, with a smile. "I suppose some people would say that was morbid."