I've been asked that question a lot lately.
Overall, I think the boys are coping with the double-whammy loss pretty well, albeit each in their own way, at their own pace.
Noah -- who remembers the loss of his grandfather the most vividly -- is probably doing the "best," although that's really not the right word. He's the most pragmatic and accepting, it's pretty matter-of-fact to him now. As I already wrote when we broke the news about Ceiba, he very literally experienced every distinct stage of grief right there at the dinner table, one right after the other. After that, he was "okay," more or less. He understood why we had to put her down and would patiently explain it to his brothers ("she's sick and going to die anyway, it's our job as her people to make sure it's not painful"). He sought Ceiba out for extra love and attention during her last days, but was also very focused on the exciting possibility of a new dog.
His rapid-fire approach to grief certainly came in handy with Max, as we had less than zero time to adequately prepare the boys for what was happening. They'd known he'd been sick for a long time, and we'd long-ago discussed the fact that his illness (kidney failure) was treatable, but not curable. He could live for a few months or a few years, he's already very very old, so let's all make the most of our time together, blah blah blah.
Honestly, Noah was mostly concerned about how visibly upset his dad was. We certainly didn't hide our emotions from them with regards to Ceiba, but Jason came home from work that day still stubbornly believing Max had months left to live. He then tried to justify a few more days, before finally I think the denial blinders came off and the crushing reality of what had to happen (and had to happen ASAP), hit him really, really hard.
Beau's presence was definitely a big help, for Noah in particular. We'd only brought him home like 18 hours before we said goodbye to Max, but it was love at first sight for these two. Beau's energy level and style of play mirrors Noah's own, and they're having a ton of fun together.
Ezra and Ike are definitely still working through everything, which is perfectly understandable. Ezra was so young when my dad died and Ike wasn't even born, so this is really their first big-time experience with death. And having two to process so close together, well, Christ. I'm right there with them.
Ezra is still meeting weekly with his school's guidance counselor, which DAMN, that's nice, I did not know that was even A Thing He Could Do. I don't know how much it REALLY is about him being so sad he needs to talk to someone and how much it's about the fact that the guidance counselor is young and pretty and pulls him out of class to play games with him (I see you, Zah) but better safe than sorry.
He and Ike both tend to bring the pets up out of the blue. "It was so sad when Max and Ceiba had to die," Ike said last night at dinner. Yes, it definitely was. "I miss them so much," Ezra said at breakfast. Yes, we all do.
They both agree that Beau is so cute and so adorable and so fun to play with. They never knew Ceiba when she was really young so Beau is practically a puppy in comparison. Ike needs occasional reassurance that Beau isn't going to die (or more specifically, that we don't have any plans to "kill" him, because we're apparently pet serial killers now). Ezra mostly just wants to know when we're getting a new cat.
(Yeeeeeeah, another question people keep asking. I don't know. I was super easily talked into a new dog but remain the sole voice of dissent re: another cat. Partly because Beau needs a lot more time to settle in, partly because I think we'd have a SUPER hard time finding a cat that would be happy in a home like ours, and partly because Max was never a typical cat in behavior or personality -- he was more like a lap dog who just happened to use a litter box. So I'm sort of afraid we'll get a cat that acts more like a typical asshole cat and I won't like it very much.)
(And then Jason makes puppy [kitty?] eyes at me because he really wants another cat and goddammit I'm probably going to lose this one eventually.)
Anyway. That's how the boys are doing. Right there with the grown-ups in the house, I suppose. Good and bad and ups and downs and getting through it all with a some help from a new furry friend.
(If there are any typos in this post, this is probably why.)