Here are some concepts you could play with:
Have a table of two fields: ID and GroupName. The ID will be the ID, and the Group Name will let you group the customers' ID together - the same CustomerID can be in many groups.
Link that table to the table you want to search in by ID=ID. Have a global field, gGroupName, in the customer table (assuming that's where the user works). Make it a text field, with a drop-down list of all the GroupNames.
You can script as much of this as you want. Attach it with a script trigger to the global field:
Go To Customer Layout
Set Variable ( $GroupName ; gGroupName )
Go to Layout (the one with the new table of IDs)
Enter Find Mode
Set Field ( GroupName ; $GroupName )
Go To Related Record (Use that relationship by ID ; Customer layout ; Show all related records)
You can amend the list as you add more customers.
You can create the list in Excel and import it to that table.
Here's a simple script that will find all records with one value in the list of values. You can paste, values into the global field this uses, type them in or even format the field with a check box group and this will work as long as each value is separated by a return. (And this can be modified to work with commas or other separating characters if you want.)
#List of IDs are first entered in global text field called: Globals::gIDList
Enter Find Mode 
Set Variable [ $I ; value: $I + 1 ]
Set Field [YourTable::ID ; Getvalue ( Globals::gIDList ; $I ) ]
Exit Loop if [$I > valuecount ( Globals::gIDList ) ]
Set Error Capture [on]