So, I have a dilemma. Once, the kids begged and begged until I finally caved and got a kitten and a…

So, I have a dilemma. Once, the kids begged and begged until I finally caved and got a kitten and a puppy (at different times, and they never lived together). We took the cat to the dacha for the summer (she's a bit of a diva and peed on the seedlings), so that's where she lives now. She feeds herself. My oldest took the puppy and moved out with him. The middle ones weren't really eager to walk a dog. And I swore then: no, no, and absolutely not. But over 3 years have passed, and last year a friend asked me to take in a kitten and a dog (we were going to the sea, the animals came to us). And I see that my kids are now perfectly fine with walking a dog and cleaning the litter box. They've completely changed. They are asking me SO much for a pet. And I'm not really keen on it. Although I understand. Now would be the perfect time for them to get one. The twins are obsessed: one with cats, the other with dogs. Maybe I should really get one? A curly little one, like a mini Airedale Terrier? And a kitty (even a regular one from a shelter). Any advice? Is it better to get them at the same time? Or one by one? I imagine it's tough to walk them, feed them? Take them to the vet? Or is it not that much of a hassle in general?