true/false afhængig af udfald ved join

Change your relationship to an OUTER JOIN. You do this by right clicking on the thin line and then from the menu choose JOIN properties. Then there are three radion buttons. Choose the one which suits your requirement.
Then in a new column in the query you check to see if one of the fields in the table you want to see if any records exist. Something like this

TF: IIf(IsNull([TableName]![FieldName]),0,-1)