Automatic workflow transition should only initiate when all pull requests are merged

We have configured our JIRA workflow to use automatic workflow transitions with triggers from Stash. Specifically, when a pull request is merged the issue is transitioned from 'In Review' to 'Resolved'. However, we have a slightly unusual setup in that we have more than one Stash repository per project and it is not uncommon for a JIRA issue to be associated with changes in more than one repository. As a result, it is quite common for a JIRA issue to have more than one pull request. Our problem is that as soon as the first pull request is approved the developer merges the branch without waiting for the other pull request(s) to be approved. This transitions the issue to Resolved even though there is still one or more outstanding pull request. Ideally, it should not be transitioned to Resolved until all pull requests are merged. I think the best way to achieve this would be to have a Condition that can be added to the transition which would prevent the transition if there are outstanding pull requests.