Got a usecase like, while authoring in a multifield dialog, all the contents present in a field will get duplicated to the other field when clicking on add button.
For Example, lets say , in a multifield we have a textfield and a numberfield and once we author both fields, next on click of add button the authored contents should reflect in this new filed added inside multifield.
Is this even possible or a valid usecase in a multifield?
First of all this should not be a use case. In my view, let's say we have a multifield which has 2 fields i.e. Text Field and a RTE field. Now when you configure the dialog for the first time, you will need to author the content for the first list item. On second list I agree that we can copy the content from first list item and it can be done by writing some additional logic. But why will someone want to duplicate the content in a list? Also let's say we want to change the content after copying and you have 2 different content in 2 list. Now for the next item when you will click on "Add" which field it will copy from? Should it copy from list 1 or from list 2? So I don't think this should be an use case!
OOTB functionality is the best one where it gives an option to add the content as required.