Lets be real, Sam Presti/Masai Ujiri/Pat Riley/Danny Ainge will likely never complete a 4 team trade as all 4 are the toughest to deal with NBA Execs. But I think this trade works for all teams involved.
The Raptors need to rebuild around Barnes, and if they don't offer an extension to Pascal Siakam he's going to sign somewhere else in the offseason. But he's not on pace to earn All-NBA, but he is going to command a 4yr 202M (30%) contract. Here, in return for Siakam, Toronto gets a return tour for Lowry, young talent in Tre Mann, a knockdown shooter in Robinson that helps with their terrible spacing, and 3 1st's in the next two drafts for a quick rebuild around Barnes. This also creates enough Cap Space for the Raptors to offer OG Anunoby a 4 year 25%+ (roughly $168m). Actual likely outcome: Raptors make no trades, and both OG/Siakam walk for nothing in the offseason.
The Jazz need to get a big haul for Lauri Markkanen while they can, and he's too good to allow the Jazz to actually be bad enough to get a top tier talent in the draft without serious lotto luck. Here, the Jazz get a return of 2 young talents (1 of which could be an All-Star one day in a position of need at PG, if his situation turns into nothing which is looking more and more likely), 3 1sts (one is unlocking their own), and 2 Swaps, all of which are in years they only have their own picks. Actual likely outcome: Jazz keep Markkanen and do a renegotiation on his contract, and never draft a star player because they always fall in the bottom of the lottery due to Lauri. Also likely lose either their own 25 or 26 1st to OKC.
The Miami Heat need to pounce on a big trade for Jimmy Butler before he starts to regress in the next few years since he's 34 already. And since Pat Riley refuses to use Tyler Herro in any trade (rightly so as Tyler is really turning into a star), they have to trade for an expiring star and likely give more than they are worth. In this trade, while they send out 4 1sts, they get back their 2025 while adding Pascal Siakam and Dennis Schroder, thereby creating one of the scariest starting 5 in the NBA with Schroder/Herro/Butler/Siakam/Adebayo. They will be sitting at or above the 2nd apron, but if anyone can afford that who isn't Golden State, it's the Miami Heat. They fill their bench with veteran min guys looking to win a ring. Actual likely outcome: Pat doesn't make a trade, and Miami gets bounced by the Celtics in the 2nd round of the playoffs.
The OKC Thunder have a 3 year window with Chet/JDub on rookie contracts where with 1 trade they can guarantee themselves as a top 3 contender in the West (and without totally throwing away their future), and have a high probability of winning a championship over that period of time (as high as anyone else). Here the Thunder send out 4 1st's, 2 Swaps, 2 talented young guards, but get back a likely valuable 2030 Heat 1st (in a year they only have their own) and one of the best 3pt shooting bigs in the NBA that fits really well with SGA/Dort/JDub/Chet and create one of the scariest starting lineups in the NBA. They will also have cap space to do a renegotiation with Lauri, and if he doesn't earn a All-NBA nod his max possible would be a adding $20m + 4yr at 25%. This would allow OKC 2.5 years to see if this team is worth going heavily into the tax for. Actual likely outcome: OKC makes minor trades around the edges, shifting picks around and might make a small trade for a bench big with 2nds that barely moves the needle. OKC might win a playoff series, but are bounced by the 2nd round. OKC continues to build from the draft and use picks to move up into the 2024 lottery as far as possible.