Thanks more to Behringer Development team for 1.12.4 update.

and now I know that there are only behringer update their digital console frequently and constantly.

I have one another idea for key source.

When operator using these technic for gating drum, users spend two channels for one source.

https://youtu.be/X7WunKmUh04?t=452

so this... If user using this tech for ever drums ( kick snare tom1,2,3 ), have to using 10 channels totaly for this.

So.... 

If users can using not only 40 input channels but also could assign every connected inputs ( not yet assigned input ch ),

Users could save 5 channels, and could using that for other sources.

Thanks for your reading.

Best regard.