dynamic update to the property

Summary: We have derived property (Custom Parent) in the custom viewpoint which is dynamically gets updated based on the movement of child member in the original dimension viewpoint. We have used that custom parent property in expression to derive property value for another property(VI Cost Centre) in the same custom viewpoint. Now the issue is the custom parent property is getting updated dynamically in correct manner based on the movement of child member. However the second property is not updating the correct custom parent value in it. Please see the attached snapshot for reference.

Can someone please help me what changes do I have to make in below expression to make dynamic for updates like this.