>Hi Naomi
>Thanks for helping. I am using version 2005.
>Yes, it's one Activity record for each date/tour combination.
>Changing Dates or TourID is allowed in the Orders table, that's why made things too complicated for me.
>If an activity record has lost all his reservations, it can be deleted...
>
>Jaime
>

I see - then it's more complex indeed and perhaps it may be better solved with a trigger (using UPDATE check).

I need to run now, post your attempts in the meantime and I'll help you when I return.