Hi,
The easiest way to know the tables involved will be through the SBO Client.
Under the View Menu, Check the 'System Information' menu.
or Short cut is Ctrl+Shift+I.
Then open your Pick List form, now if you hover to any of the item in the header you will find something like
at the status bar below you will see the table name OPKL.
following SAP naming conventions, the child tables will be PKL1 and PKL2.
Regards
Edy