Hi Marcel,
if i understood you correct I would do it as follows:
- Add a data view or list view for the columns entity
- Within the data view or list view, add a data view or list view for the entries entity. This nested view will display the entries associated with each column
- Inside the nested data view or list view for entries, add a text box widget to capture the string value. Bind the text box widget to the appropriate attribute of the entries entity
- If you want to allow users to add multiple entries for each column, you can include a button or link that triggers an action to create a new entries entity and associate it with the corresponding column