Thank you so much for your replies, Karl.
The animation is kind of rudimentary in Archicad, but I decided to see what I could do with it while I was there... I have my OCD to thank for that ; )
I did manage to figure out the 'relative position' scripting (for each frame), and concocted something that looks pretty good (for what it is), enough to use, anyway.
And the 2d symbols disappearing: this was due to my not creating one upon creating a new object in 3d view. I managed to set that straight by creating a 'temp' object from the original in 2d view, and copying the script from that over to the 3d-made object.
I hope this works here... attaching the finished film.
Thanks so much for your advice!
PS: nope, so attaching link to my G+ drive: