How story rank is affected when re-ranking an epic

[Jan Kips]

We have a list of >150 epics (most of them containing stories) that we are weekly (re-)ranking in Portfolio v2.x.

The main issue we're facing is that - when changing the epic ranks - the story ranks don't get updated the way we want them to be.

What I found out is:

• Rank epic A down under epic B means JIRA/Portfolio re-ranks all stories of epic A under the highest ranked story of epic B.
  Note: this is not the behaviour we expect, because we would like ALL stories of epic A to be ranked under the lowest ranked story of epic B.
  
  Likewise for ranking up: 

• Rank epic A up above epic B means JIRA/Portfolio re-ranks the highest story/ies of epic A above the highest ranked story of epic B, but not all.

The problem with this is that the scheduling gets distorted.

Consider this example:

• We have 2 epics: epic A with stories A1 and A2, and epic B with stories B1 and B2.
• Assume that epic A was ranked above B originally, so the stories would be ranked A1 > A2 > B1 > B2
• If I now rank epic A below B, then the ranking will be B1 > A1 > A2 > B2.
• As a consequence, when calculating the scheduling, epic B will only be completed after epic A, because of the lower ranked story B2.

We have this issue with hundreds of stories, so looking for an elegant way to solve this. Manually dragging all stories to the correct rank upon changing an epic's rank is not an option for us.

Grateful for your feedback or thoughts on this!