More control over UI User Story Map: Features organized in 2 columns under a single master feature & step

When working with many features, it is important that Features in User Story Map can be organized in two columns or more under a single master feature and single column per step. Currently each column  must have a master feature * at the top of each column of features (where two columns have one user story map step)

*1 - master feature is not mandatory but if working with many feature it is needed. 

Why is it useful? To visualize on one page the groups of features under a single step (and there is a single master feature). Today I have the list of features over two pages. It will benefit the POs and any one viewing the user story map. 

How should it work? It should simply allow the user to select the action they want to take (with a submenu)... rather than try to predict what the user wants to do. The example from above: I want to add a feature within a column, the UI thinks I want to create another column.  

There are many other examples where it is difficult to have the UI do what we want. i.e. the interface is highly complex and given the many options we could do, the program selects only one and executes against it. the examples are: expand a column, or add a release row, (or not add a row).... delete a row (not available), group a set of card to move them, etc.  Delete a column work works this way... really good. Perhaps other actions "sh/could" work this way. 

You know your product best.... I would like more control and for UX to be more predictable/intentional. (& less work moving many features around....  )