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I need an input on demand question. 
If I set “input on demand” as mandatory and if I have up to 6 possible inputs, but only need at least one, I get the error that the question is mandatory even if one has been completed, (only one is showing on the screen) it requires me to fill in all 6 possible inputs. How can I fix this, please? 

"input on demand" is only a visual effect.
If "mandatory" you have to answer all cells.

So the question must not be "mandatory" and you have to use a validation equation to make sure that at least one row is answered.

Joffm