Insert multiple records from 2 tables in 3rd table

Question

Many thanks for reading my question!

INTENT: to write a query that can create records in [jncListQS] of glossary terms [tblMASTER].IdTerm matched with a ListName [tblQS].IdQS

note: tblMASTER and tblQS are already filled with data; jncListQS is empty.

USER selects (by checkbox) multiple records [tblMASTER].[IdTerm] in datasheet view
and
then USER selects 1 record (by combobox) [tblQS].[IdQS] in an interactive form.

Then, USER presses button >> "INSERT or ADD selected Terms to chosen ListName"

I had planned to retrieve the IdQS using a parameter query but i can't get the syntax right.

I'd like to used queries, nested or otherwise.
Do i need to do a loop,  or ?     ----------    many thanks in advance