How to make a column a "ref" to another table and allow multiple choices selected

[Tiger1]

I have one table referencing another (customer table).  i want my user to be able to choose mutiple customers.

This is a list of my users and the customers they are allowed to view.

[TeeSee1 · Accepted solution]

I sometimes wonder how dropdown lists are controlled myself. When setting REF doesn't work I set VALID-IF or SUGGESTED VALUES expressions. This works everytime.