You can get the results you want, but not by using the exact features you are trying to use.
Instead of custom values, place each list of values in a separate table where one record = 1 value. Put all the values from all three lists in this one table. Use a second field to identify whether the record is a list1, list2 or list3 value. Given your description, make this a number field with 1, 2 or 3 in it. Let's call the value field "Value" and the list membership field "ListID".
Now you can use a concept called a "conditional value list" to select a specific group of values.
Define a relationship linking MainTable :: Master List = ValueTable :: ListID
Now you can define a value list to specify the "value" field in ValueTable. At the bottom of this dialog select the show only related values starting in... and specify your "MainTable" in the pop up.
Now you can select a set of values by clicking 1, 2 or 3 in the radio button formatted Master List field.
To edit these values, place an "edit" button on your layout that takes the user to a layout that displays the values and allows them to edit them. You could even pop these values up in a new window to more closely mimic the behavior of the Edit option for custom value lists.
Awesome idea - I'll give it a whirl tonight! Thanks Phil!