Inserting multiple list elements using an action




I was wondering if you could help me with a problem I am having.

I have a numbered list A where the user would like to insert some elements without using the 'Insert' option, but instead by an action.

Before, the user inserts the desired number of elements of the list A from 1 to 1000, as it is a numbered list, there are unique keys.
A module (X) allows to assign for each unique key a code and an action allows to import in the list A the code and the parent that we have in the module (X).
module (X) is sized by the list A.


Since the user wants to create items in list A using an action, I need to know how to automate this process.

I need to create an input module Y so that the user can insert the new keys he wants to have in list A (For example in list A we are already at #10000, if the user wants to enter 2000 more rows, he will go through module Y  and create 2000 keys from #10001).
My question is how do I create this module, with which list and how do I make the link with the list A to be able to assign for each key a code using the module (X)?

I need to assign a code for each new key entered by the user in module Y using module (X) to import in the final list A the new list elements.


Thanks in advance for your help and remain open for any other solution.