How to insert data into other tables which are not visible in the screen?

How to insert data into other tables which are not visible in the screen?
For example , I have sales master and sales details tables which are visible in the screen and daybook table for accounting purpose which is not visible in the screen. I want to insert 4 or 5 rows into daybook table for a single sales entry. daybook table or entity will not visible in the sales screen. How it is possible ?

Please look at this sample application: https://github.com/cuba-platform/sample-data-manipulation
It is also available on the Samples tab in Studio.