If it is more complex to determine the data set, because you have specific parameters in mind it makes sense to select the data via SQL and insert the selected record into the other instance via SQL. You can either use linked tables, which allows you to write this simple logic in Caché Object Script, or you can write a simple Java application and go directly via JDBC. Obviously, any supported client-side language can solve this challenge, Java is just one option.
This approach is definitely more work than just exporting/importing the data, but it allows to easily add simple logic with some benefits, e.g. anonymization, batch-loading and parallelization. Depending on your use case some of these topics may be relevant.