Editable shared columns on a document set

I have a customer that would like shared columns in a document to inherit from the document set. However they also want to option to change the column afterwards to another value than the document set. I cannot see that option is possible. Any suggestions on how to solve this? Would it be possible to make a flow that takes values from a document set and add it to none shared columns on the documents created within the document set? Or how would you do this?