Dependent OVS Custom field in s4 hana using Key User Extensibility

[Pyae_Phyo_Thwe]

I have create a custom BO with header level and item level
I want to add two OVS type custom fields in Manage Sales Order app. 
The first OVS field will show the header level data of custom BO that I have created. 
The second OVS field need to show the item level data of chosen header level data in first OVS field. 
It's like I want the dependent OVS fields.

Below is the way I have tried. 
Step 1 : Create a custom BO with header and item level. 
Step 2 : Create a Custom CDS view with the Value Help scenario type. In the elements tab, added the elements that I need and made key to both headerID and itemID
Step 3 : Create Custom field with the "Code List based on CDS View" type using the custom CDS view created in Step3. 
Step 4 : Add the custom field to "Manage Sales Order" app. 

The result  : 1. Both OVS fields showed all header and item level fields. 
         
Header Level OVS 

        

Item Level OVS      

   
    2. I need to clear the filter value in header OVS field if I want to choose second time.

Filter value added when choose the value in header OVS

What I want : Header OVS need to show only the header level fields and item OVS need to show only the                               item level fields. 
                       I don't want to clear the filter value and the OVS field should be able to choose as much as I                             want. If the chosen header ID is changed, the value in item OVS should also change.

Header OVS I need:

Item OVS I need: The info is shown based on the chosen data in header OVS

  

Does anyone done like that development in S4 hana using Key User Extensibility.
Could you please provide the documentation or any idea?
Thanks in advance.