Create custom sublist in Case Record to display cases associated to the customer

A. Create a Case saved search to be used on the Custom sublist

1. Go to Reports > New Search
2. Click Case
3. You may opt to leave the Criteria tab > Standard subtab > blank
4. Under Results tab > Columns subtab > add the fields needed based on the user's requirements (see below as an example):
• Company
• Number
• Subject
• Status
5. Under Available Filters, add Company Fields > Internal ID 
6. Click Save

B. Add the Saved search to the custom sub-list on Case Records

1. Go to Customisation > Forms > Sublists
2. Under CRM tab, choose the Saved search created above
3. Under Label column, add a name of the custom sub-list
4. Mark Case
5. Under Field column, choose Company
6. Click Save