Retail POS : adding new additional fields to customer search

Dear All,

I am a beginner for the Retail POS customization. :)

I want to add two more additional fields on the Customer Search screen on the Retail POS.

So far what i did was to adding the fields (ID and the Document No) on the screen via Visual Studio and upon customization the screen looks like as below :

Now the next step is to bind those fields with the database.

With the research i did so far it seems i might have to customize the Microsoft.Dynamics.Retail.Pos.DataManager. I am not sure whether i am right or not. 

how can i proceed on this? 

thanks in advance,

Ammar