Delegation of approval rights

Team,

Please let me know if there is a feature in JIRA Service Desk where a user with a customer role, that has access only to Service Desk Portal, can delegate his approval rights for a certain period of time?

Example: We have set up a request workflow that requires Business Unit manager approval. Since we have different managers for different teams, we have connected JIRA SD to our Active Directory and for each request Reporter creates we use a plugin to pull the Manager attribute from his Active Directory account and set it to be an approver for that Request.

Question: Is there a way for the Business Unit manager to temporarily delegate his approval rights, by himself , to another user, while he is on vacation, let's say next 15 days.

If any further clarification is needed please let me know.

Thank you.

Miroljub