I'd do Simons, Hauser, and a bunch of 1st's for Sabonis (it will require way more than 2), but I think that is likely way too expensive so White or Brown would probably have to realistically go out. So if they'd swap Simons for White (and maybe 2 less 1st), I'd probably do that. For team balance it may make more sense to trade Brown. I'm not sure he'd make sense there, but a 3rd team could work.
Maybe something like this
Boston - Sabonis, Sochan, SAS/ATL 26 1st
San Antonio - Brown
Sacramento - Castle, Olynyk, Castle, SAS/BOS 28 1st
So Boston picks up a starting center and power forward for Brown (along with a 1st), Sacramento shaves a ton of salary while picking up the ROY and a future 1st, and San Antonio goes for it adding Brown to Wemby, Fox, Harper, Bryant, Vassell, Johnson, Kornet.