Thanks very much for responding.
I did find a solution. It looks like your suggestion might be a more elegant way of doing something similar, and I would truely like to understand it, but my way is working and I have to get this thing looking pretty now and delivered.
What I did is cause the StringVar that gets checked in Record Selection to be populated one iteration late.
Now I have this in a field in the details section:
Global StringVar D;
Global StringVar D2;
if ((totext({Activity.StartTime}) in D) = True) then
D2 := (D2 & totext({Activity.StartTime}));
D := (D & totext({Activity.StartTime}));
and this in the Record Selection:
(totext({Activity.StartTime}) in D2) = False
This works perfectly in testing. Let me know if you see anything wrong besides uglyness....
Thanks again for your time.