VARI to FIXED on one channel only

Can a MIX bus be changed from VARI to FIXED on one INPUT channel only?

(PM1D, PM5D, M7CL, LS9) No, it cannot. The bus setup is global for all input channels.

(DM/0) No, it cannot. AUX can be used as GROUP by changing its mode to FIXED. But, the mode is global for all input channels.

Note:
VARI (Variable) = AUX
FIXED = GROUP