Currently, Crucible is designed to only handle a a single "parent" JIRA Issue, so that it can create sub-tasks from review defects off it if needed. You can still reference other JIRA issues by including them in the description. However, the Crucible review link only appears in JIRA on the Review tab for that one parent issue.

In some circumstances when there are multiple JIRA issues and revisions that apply to a file, it is easier to launch a single review with the first and last revision for comparison, rather than multiple reviews on each revision. I would love a new feature that allows me to set "secondary" JIRA Issues for reference/integration purposes only, so that I can have that single review show up on the Review tab of multiple (related) JIRA issues. I don't need those "secondary" JIRA issues to have sub-task creation capabilities.