Simple Access/SQL project?

I'm trying to build an Access form that will change data in 3 separate tables in SQL. I have the ODBC link created and I can see all of the fields. The issue I'm running into is I can't get the key ID to update in the two sub tables from one field in the form. I created the primary key ID and made the other two tables have a foreign key relationship to it in SSMS. What am I missing? I'm sure it's very simple but I've been searching for hours. This is my first time dabbling into this software so any help is appreciated. Thank you!