Hi Anass
To add a “Deal” column to the left list of the Price Entry (GESSPL) screen so you can filter price listings by deal:

Identify the Object used by Price Entry
Use the Window or Function dictionary to find the correct Object that controls the left list.

If “Deal” is in another table, link that table

In Development → Script Dictionary → Objects → Environment tab, add the related table and its link expression so the field becomes available for selection.

Add the “Deal” field to the left list
Go to the Selection tab of the same Object and insert a new line selecting the Deal field.
Save & validate — the new column now appears in the left list.
Filter by Deal
Once visible, users can filter by Deal using the left list search or Advanced Selection (with optional saved Memos).

 https://communityhub.sage.com/us/sage_x3/b/sageerp_x3_product_support_blog/posts/enhancing-the-left-list-in-sage-x3-v12p37 

https://online-help.sagex3.com/erp/12/en-us/Content/FCT/GESAOB.htm

https://online-help.sagex3.com/erp/12/en-us/Content/FCT/GESSPL.htm

For further assistance, please contact your local support for assistance.