Had no idea it'd be this complicated! Those "old school" methods are daunting; much more work than I'm doing copying individual items. I fell back on RedPhantom's method. I put a group of table and four chairs in my prop library and import it into the scene over and over until I have enough tables. I just thought there'd be a quicker way, like in other 3D programs: copy-paste-paste-paste. Ohki, I created a grouping. In the hierarchy editor I dragged a table and four chairs into the grouping. The grouping moved and scaled together. So far so good. Then I chose edit>duplicate grouping 1. A new grouping, Grouping 2, appears but it's empty. I'm sure I'm doing something wrong but I'm not sure what.