Ability restrict the options of Portfolio/Roadmaps "Parent Link" field through behaviours

Summary

As a Jira Admin,
I want to control the options for the Roadmaps Parent Link field using behaviours,
so that I can automatically restrict the issues that a user can select from this field.

Details:

The `Roadmaps for Jira` Parent Link field displays a list of Issues that are valid parents to the issue type you are currently working with. (Roadmaps for Jira lets you create a Hierarchy to define which issue types are valid parents.)

Users would like to use behaviours to restrict further the Parent Link fields issue options.

For example, the hierarchy may let users choose issues having any of 3 issues types. However, users want only to allow 2 of those Issue Types if the current issue has a given value selected in one of its other select list fields within the same form.