Limiting And Filling Fields Based On Another Field

The database I am building is for Student & Alumni administration at a non-profit culinary school. In the various forms for entering student information and for defining tests and recording test scores, I would like to not have to re-select things like Class Number or Test number.

I was able to use the Test Number field as Link Master, Child in a Test Results sub-form where Test Parameters is the Master form. But I am not able to link with the Class Number, getting the error message: "The setting you entered isn't valid for this property" even though it is one of the Suggested Link Fields. The form record source is a query linking the Class Table, Test Parameters, Test Results and Students.

I noticed that I can eliminate both Class Number and Test Number from the sub-form. In the underlying query, both these fields are updated. However, the underlying Test Results table does have the Test Number but not the Class Number. While there is still a "queryable" link from the student to the Class Number, I would very much want the Class Number to be stored in the Test Results table.

Is there a way to accomplish this through the sub-form Link Master/Child property or any other/better way to inherit both the Class Number and Test Number in each Test Results record entered?