I would like to plan, review capacity, and keep in sync with JIRA issues through portfolio in a way that does not cause headaches for the rest of the team.

What I would picture as a feature, would be the capability to assign a team to an epic/issue in Portfolio, but create a Portfolio configuration setting to leave an issue unassigned if the issue is currently unassigned. The portfolio could still forecast capacities based on team member hours and skills.

In the classic portfolio, I was able to accomplish this by creating a fake team member with the same number of hours available as the real team members combined. I would then assign the "unassigned" user to all epics and stories that were still in the planning process. I was effectively doubling my teams capacity in the eyes of Portfolio, so for the trick to work, I had to make sure to assign all issues manually to team members (real or unassigned) so I could maintain control over capacity.

I would like to have the ability to manage my capacities, while not yet being certain which developers would do the work. My biggest headache is having portfolio assign team members to issues, having my updates and improvements on those issues slam their dashboards and emails, and knowing that the issue may not actually be assigned to them.