I like the 2nd scenario:
Use this auto-enter calculation with the "Do not replace..." check box cleared:
If ( IsEmpty ( FilterValues ( Self ; "Recommended" ) and Not Isempty ( Recommended By ) ; List ( Self : "Recommended" ) ; self )
How it works:
When you click check boxes in a group of the same, each clicked check box adds a value to the field separated from other selected values by a return character. List ( "value1" ; "value2" ) produces the same return separated list of values and List ( Self ; "recommended" ) appends "reccommended" to the end of any list of such values already present in the field.
almost there...but not yet... I entered the calc you gave me (thanks!), and only needed to make two changes (otherwise, I couldn't close the calculation dialog box).
The changes i made were: 1. added a "close paren" to complete the "test" portion of the IF statement, and 2. In the "result" portion, i changed the colon after "Self" to a semi-colon. Then i also cleared the checkbox for "Do not replace..."
But, as you can see from the screenshot, "Recommended" is still not getting checked when there's a value in the "RecommendedBy" field. Thoughts??
Voila! It works. What a team! thanks, again.