I concur with aytee111.
Access implements MVFs with an
internal junction table, simply hiding the
added complexity from the user. One of the big limitations of MVFs is related to integration with, or porting to, other DBMS, as the junction tables need to be rebuilt first. While MS added MVF fields for simplicity for beginners (non-programmers), MS
did not fully integrate MVFs to make them usable. MVFs break normalization rules because the fields are not Atomic; ie MVFs break the
First Normal Form (1NF) rule.
This is why most experienced Access programmers will not use them.
In any case, because you have a MVF, you will not be able to sort the selected values in the two combo boxes.
See
Multivalued datatypes considered harmful (2 pages)