You should be doing it by unique key values, NOT by name. Each table of your database should have a primary key (unique ID like a serial number or UUID), then tables should be related by foreign keys that reference those primary keys. EG If I had a customers table, with an ID field, I would tie a Sales::customerID field to that primary key to relate Sales and Customers.
That said, searching by any variable value is easy with a script:
Set Variable [ $key ; yourTable::valueToSearchField ]
Enter Find Mode [ no pause ]
Go To Layout [ layout you are searching on ]
Set Field [ tableSearching::fieldSearching ; "==" & $key ]
Thanks for your advice Mike, I will give it a go