Non-Linear Manuscript Plot Grid

Say you want to write a whodunnit story (or a Memento novelization!) and have the common flashback scene that explains how the murder actually took place near the end of the novel. The current "Manuscript Plot Grid" is good for putting the scenes in chronological order. However it would be very useful that in the tree structure of the novel I can put that (or those) scene(s) up or down the story WITHOUT affecting their chronological position on the grid.
So, basically untie the first column (linear succession of events) from the tree structure positioning of scenes. It's ok for it to suppose the scene that chronologically occurs after is to be put after the last one. But I'd like to be able to move it afterwards.
Let me know what you think!