dont take this the wrong way, but what are you calling low verses what it says in the submittals? Not trying to be smart, but we often see crazy designs anymore where they are trying to use lower leaving air temps for a variety of reasons. Hell, we got two units running at 36 sst and 42 leaving air. its difficult to get them setup right without frosting the coil. you lmost have to sit and read the submittals first anymore to see what the hell they want.
As a side note, we got another unit running at a design of 136 condensing with R410, fun eh?
The staging: I have as follows to prevent LSST. The condensers are 2 carrier gemni select. Each one has 5 compressers, circuit a 2 tandem, b 3 tandem. One is a master other slave, when they get y1 call it gives the units permision to run 60 percent capacity to maintain 63 degree discharge air, y2 gives permission for 100 percent to maintain 58 discharge air. Doing it this way only helps to prevent all the compressers to run on same circuit at sametime unless load is high enough to keep suction pressure up, also with the lead lag it keeps the evap with no dry spots for air to pass threw easily. But its a numbers game the true fix is my suction pressure with 10 to 20 degrees superheat and smae subcooling my suction is between 85, 100 with 410a. Pipping is sized, cfm is there, static is less then mfr.
basics....get subccoling close to being right, then adjust to proper superheat. do each circuit with the other one turned off.
10 to 20 subcooling, the problem with adjusting and charging each circuit seperatley would leave sections of the evaporatorfew with no condensation and give air a path of least resistance not getting enough air just adds to my problem.
I would shoot for more like 8-12 then adjust superheat. dont overthink it. a coil is going to create some resistance, and you shouldnt care about the bypass. there is plenty of load on the coil you are working on.