So who was the Jonas Brothers’ Yoko? You may come to the new Amazon Prime documentary about the trio, “Chasing Happiness,” chasing an answer to that whodunit about who broke up the sibling trio at the end of their first run together. (Of course we invoke Ms. Ono as a mere pop figure of speech, knowing she is a fine artist and the Beatles were grown men capable of making their own decisions, etc.)

Although the documentary doesn’t offer a firm conclusion, you may come away thinking it’s a tie, and between some “whats,” not “whos.”On the one hand, there’s a firm argument to be made for the head-swelling combination of “Nick Jonas & the Administration” and “How to Succeed in Business Without Really Trying,” the youngest and most ambitious member’s first big side projects. But a good case can also be drafted for “Married to Jonas,” the E! reality show that finally gave Kevin a turn in the spotlight but forced Nick and Joe onto the air as unwilling supporting players near the height of their tensions.

There are several ironic moments in “Chasing Happiness” where we see the lads doing TV interviews in which they’re asked if they could ever split up and they say, no — how could brothers break up? Obviously not big Kinks fans, these three. And the lessons of Noel and Liam Gallagher, who only went their separate professional ways in 2009, were perhaps a bit too fresh to sink in even if the Jonases were precocious pop historians. Who’s going to warn ascendant teen co-heartthrobs that ego is thicker than blood? Nobody, apparently.

Of course this documentary would not be happening — or at least would not be produced by Philymack — if there weren’t an upbeat ending in the form of their just-released, well-received reunion album, as well as many happy therapeutic returns as the guys talk out and hug out past resentments. But if you’re honest, it’s the middle act you come for in this kind of a story, clashes being ever so slightly more interesting than redemption. Given that any doc produced by an act’s management company arrives with suspicions that it’ll be a glorified EPK, that middle act here is a good, surprisingly candid one — and, actually, the plucky bookends aren’t bad, either.

Very early into the doc, we see a video of Kevin and Joe coming into a hospital room to greet their new baby brother, as we hear the arrival in question, Nick, say in voiceover that “from the very beginning, my brothers and I were always…” You start to fill in the obvious end of that sentence — “…on camera” — a split second before Nick instead says “…very close. The image the Jonases tried to portray as scrappy underdogs from Jersey was partly misleading, as you probably have to give up the working-class tag if all three brothers were doing Broadway and/or commercials before they got into either pubescence or pop. But the “poor” part was true, especially after their dad got nudged toward quitting the pastorate, and they had to move out of their suburban rectory right around the same time Sony dropped the brothers without ever releasing an album.

For as much publicity was given as there was at the time to the Jonases being “PKs” (largely as a result of the fascination over the purity rings) — it wasn’t so well publicized at the time of their rise to stardom that they were an ex-preacher’s kids. As the film has it, at least, the church loved it when the lads were on the worship team, but the Assembly of God denomination tends to be a little less accepting when every song is about puppy love and you’re not trying to sneak at least a little Jesus onto “TRL.” And so the group’s initial microburst of success with one bop on Sony that got them onto MTV apparently spelled doom for their church life and Dad’s entire livelihood. They got it from both sides, naturally, as recalled via some pretty funny clips from “South Park” that portray their later label boss, Mickey Mouse, forcing them to keep on the rings… and some much less funny clips from the MTV Awards that have host Russell Brand mocking them to their faces, and coming off as quite the schmuck about it.

It doesn’t get to the downfall too quickly; the film allows some of the joy of Jonasmania to set in once a rescuing Disney does come into the picture and figure out how to record as well as market them. There’s a great scene of brotherly camaraderie captured in a van on the way to an arena show that shows Kevin nervously on the phone urging his future wife to attend, while Joe and Kevin whisperingly ply him with less shy-sounding lines. Those few minutes almost make you believe, as they must’ve, that it would be possible to be the Beatles and a normal American family.

Then they finally get the time-out they’ve longed for, and Nick uses it to try out a side project with “real” musicians that satiates his thirst for cred, and it’s a dud (although the movie doesn’t say so), and Joe responds in kind with his own solo single, also a dud (the movie does say so), and Kevin realizes that he can be a reality TV headliner in a way he never was in music, alienating the others… and they all return to the group not refreshed but super, super cranky. “We hate each other, basically,” Nick admits. As they all recall it, Nick calls a meeting where he broadsides them with the news that the band is over. “I felt betrayed,” says Joe. “I felt lied to. I felt angry. Numb. … This is what I loved more than anything, and (that) somebody that you loved and cared about so much could take it away from you so quickly, that was heartbreaking.”

Things go from crap to worse when Joe and Nick decide to fulfill a contractual obligation by doing a few post-breakup and, oops, forget to inform, much less invite, a certain guitar-playing third wheel. “Now as I look back on it, I realize how f—ed up it is,” Joe tells a wet-eyed Kevin to his face in one of the contemporary scenes, “going to take a Jonas Brothers gig and you weren’t on stage.” Kevin looks still heartbroken and refrains from echoing the viewing audience’s collective “duh.” (“I think that might have been the hardest moment of my entire life,” Kevin admits, which is a lot more karmic weight than any Jingle Ball was ever meant to bear.) Truth be told, this was probably actually something pretty close to justice if you view it as justice for the other two having to sign releases with E! as day players on Kevin’s show, but ours is not to arbitrate at this late date.

The earliest “healing” scenes in the movie, of the boys-to-men talking through the old days atop an ocean bluff in Australia, with cameras both in front and behind, feel so stagey that it doesn’t bode well for the rest of the doc. But once it gets to that kitchen countertop drinking scene an hour in, where the guys open up some pretty old wounds that never closed — with Joe admitting he thought Kevin stopped being a serious music pro once he decided to be a family man, etc. — s— does get real. So real that you don’t leave the doc thinking they’ve all completely gotten over it, which is a solid recommendation for what could’ve been a vanity project.

There is still some vanity involved, in what was left out. It’s mentioned, naturally, that Joe and Nick both had solo success after the breakup, with “Jealous” and the DNCE hit “Cake by the Ocean,” respectively; not mentioned is the fact that they’ve both had their last three years of singles mutually fizz out. It’s understandable why that might go unremarked upon in an officially sanctioned documentary: No one wants to think the Jonases got back together because they really, really needed to, and not out of the goodness of their healing-craving hearts. But that actually would have added some suspense to the outcome. With the solo careers not thriving, it wasn’t a given that their comeback would be greeted with mania. That “Sucker” has turned out to be one of the year’s big hits is closer to a surprise twist than an inevitability, something the movie would have been better for milking at the end.

But “Chasing Happiness” is not a documentary that inspires a great deal of cynicism. There are rooting interests naturally to be had here, not least of which is that the music itself has been a byproduct of talent and always been charmed — even first smash “Year 3000” is something they won’t need to feel bashful about including in their set into the 2030s. There’s also some vindication in the good guys winning, versus the Russell Brands of the world (not that he has not gone on to do more productive things in his life, too). Yes, the medium pretty much ordained the “pop musicians, heal thyselves” outcome here, and yes, the problems they’ve overcome are first-world ones. But getting the pompons out for families becoming belatedly functional never goes out of style, just like “Lovebug.”