Yet Another Conditional Value List Question

I have a conditional value list question...

basically, I have three tables (among many others) in my database (stripped of all other fields and shown below in colors) Timepoints, Exams, and Exam Sessions.

I've created a second set of tables (below in grey) that describes the possible values for the main field in these tables named Timepoint Types 2, Exam Types 2, and Session Types 2

The possible values are hierarchical—that is, a specific "timepoint Type" value in the Timepoints table constrains the possible values for the "exam type" field in the Exams table, which in turn constrains the possible values for the "session number" field in the Exam sessions table

My question is...how do I define the relationships (and the value lists) so that when a user selects one of the available values for the "Timepoint Type" field in the Timepoints Table (value list supplied by the "Timepoint Type" values in the Timepoint Types 2 table) it restricts the available values that they can select in the related record in the Exams table? and then how do I set it up so that the choice in the Exams table restricts the available lists in the Exam Sessions table? My attempt is shown below as well?

any thoughts? andy sample files would be much appreciated as well...And I must apologize for the unpolished (and perhaps unclear) nature of this post in advance...I'm in a bit of a hurry as I type this...

thanks so much