I tried some similar yesterday… but yes, it’s complicated.
But that forced me to have 2 different forms; that is, with Inline List the data is saved in another table, not the main form, and then there was no way to relate the data from one table to another for the same user, plus it adds unnecessary rows, I think.
The trick is to create a single relation between the table where the Inline List is sourced from, and the table/row that your screen is attached to. Then when a user selects an item in the list, you can use a Set Column Values through this relation to set the value in the column that your choice component currently updates.
No extra rows are necessary.
I should add though, depending on the overall context, this method may not work. It depends which type of form you are using, and whether or not it is attached to a table row.