EDIT - will create a new post, get a bit more visibility.
Moorthy / vsmazhevski - How do you introduce a sg500x-28 into an existing sg500-52P stack (3 units) without breaking configuration?
SG500's are stacked as device 1 <-> cu1m(cable) <-> device 2 <-> cu1m - device 3 - cu3m back to device 1.
1 - Change the stacking mode to hybrid (basic or advanced?)?
2 - unplug cu3m from device 3 and plug into to sg500x (new! device 4), add in additional cu1m from device 3 to device 4 to complete the stack, power on device 4 and hope for the best?