Saving data from Matrix-Input, even if user only answers a subset of questions.

[OffByOne37]

Hello is there a way to save the answers from a "matrix"-input, even if the user does not answer all questions?

I thought of two possibilities:

• Add a default value via "selected". However this does not work -> if you create an own input type it also only works partly, since "checked" get's added but it is not saved.

• Update the values when the survey is loaded, so that one answer is already picked. But "updateRadioButtons" does not work neither.