Let me clarify once more: CASIO WK-1630 does NOT have that problem (split). Only DGX300 has that problem. DGX202 and PSR292 does NOT have the problem but they lack reg memory ability.

Pls note that SPLIT mode allows the keyboard to be divided into 2 sections (Left and Right hand). But the right section should allow 2 voices to be layered (the good keyboard). CASIO WK1630, DGX202 and PSR292 are OK here. Your understanding that keyboard can be divided into 3 sections is not correct.