If it's 20 mil over 3 years, DA still has a good deal of room for maneuvering.
Assuming that KG gets paid $11 mil next year, that Bass is for $7 mil next year, and the rookies came in for slot, DA's at $59 mil after signing Bass.
If Ray comes back at the $6 mil per season, that's $65 mil.
In order to use the larger MLE that he's agreed to with JET, the payroll can be no more than $4 mil above the luxury tax level. This has been reported as $74 million, because the CBA agreed that the minimum the luxury tax could be is $70.3 mil, so a "hard cap" of $74.3 mil is the number we mostly look at. However, back in February, the cap was projected to be somewhere between $60-$61 million. This would move the luxury tax range to between $71.7 and $72.9 million, meaning the true cap could be between $75.7 and $76.9 million.
Using the lower of the two numbers means that if we get back Ray, we could pay over $10 mil to Green. Supposing Green gets about $7 mil next year in a deal of similar size to Bass, that could leave us with between $3.7-$4.9 to go after Krstic with, or plenty of room to fit someone in under the Bi-Annual. Furthermore, signing Krstic would mean releasing Sean Williams from his partially guaranteed contract, saving us another $900K to give to Krstic.
Mind you, these numbers could be off a little, but I think they're pretty conservative/likely. I'd expect the C's to add Kristic, as I doubt he'll get the mid-level from anyone, unless they surprisingly break the bank on Green. Depending how the salaries are structured, they might have enough room to go after someone else with the Bi-Annual, but I'll think they'll keep that bullet in their chamber to ward off potential Stiemsma suitors.
Unfortunately, if they don't keep Ray, the numbers look about the same, only the C's will probably not be a tax-paying team at all, since there is no other exception available to pay someone the $6 million set aside for Ray.