What do you EXACTLY want to do?
1. Show the congregation in prayer in a rendering of the hall
2. Show the figures in your construction documents
?
If 1, Erika's advice is the best. I would make the billboards using ArchiFacade and place them accordingly. Yes, quite bit of work ... You can do the same for Artlantis.
If 2, use the 2D outlines of people to illustrate the relationship of the seated/standing people and the space designed.
Djordje
ArchiCAD since 4.55 ... 1995
HP Omen