Allow Delegate Approver to Access Change Requests Using Mandanten Restriction Query

Hi all,

I have a requirement that users can only access Change Requests if the Service (affected.item) is supported by them (support.groups in device file is an assignment group of the user).

I set up a Mandanten Restricting Query as below:

File Name:
cm3r

Restricting Query: 
affected.item isin $G.cust.service|current.pending.groups isin $G.approver.list|current.pending.groups=$lo.user.name

$G.cust.service is an array in login.DEFAULT storing the services supported by the user.
$G.approver.list is an array in login.DEFAULT storing the groups of which the user is an approver.

Now the problem is, when user delegated approval to another user, the delegated approver cannot access/approve the Change Request. How can I fix this?

Many thanks!