How to create plan scenario with adittional issues added

[Vesna Juric-Kapor]

We want to play with plan scenarios where a management comes in and ask us to take on a new project on top of our existing plan and ask us to finish it before the certain date. We would like to create a scenario for our existing plan by adding issues from this new project.  We would put in some ballpark estimates for each issue and assign people but would like Portfolio for JIRA to schedule those additional issues for us so we see if it can be done by the requested date or not. Is this possible to be done and how? Thanks for the help.