Hi JD,
if you want to display the user field values from multiple lookup table then the below query will helps you, Assuming all your lookup(USECASE1,etc) contains user field named user.
|inputlookup USECASE1 | table user |append[|inputlookup USECASE2 | table user] | append[ | inputlookup USECASE3| table user] | stats count by user | table user
If you have the different field names in other lookup you can rename it, as like the below search
|inputlookup USECASE1 | table user |append[|inputlookup USECASE2 |rename user2 as user | table user] | append[ | inputlookup USECASE3| rename user3 as user | table user] | stats count by user | table user
If you are looking for a list of lookup table available across the application and user this will help you.
|rest /servicesNS/admin/search/data/lookup-table-files | table title
if you want you can retrieve based on required user / app etc..
Hope this will help you.
Cheers!