>>>Could one account have two owners, one permanant and one temporary?
>>>Also can you use UNION or not?
>>
>>Theoretically - yes.
>>
>>Yes, I can use union, but note, that I want to group by.
>
>Did second suggestion works (this with IIFs)?

Looks like it may work (I'm looking at it right now). The only correction while I'm looking - instead of empty I need to use IsNull. Let me look a little bit more, than I try it.