I was unaware of instance arrays, now I see what you mean. Yes, if I name the instance "name<m:1>" in the schematic, then generate it in the layout, it will create a row of the devices with some arbitrary spacings (hopefully the DRC minimum), and I can place them as a group. No interconnects are generated automatically. Strangely, if I make a two dimensional instance array, the result in the layout is still a one dimensional array, with a number of devices equal to the smallest dimension.
Somewhat helpful, but not really useful for common centroids. Is there a way to change the spacing of the arrays when created in the layout? If I could double the spacings in one dimension, then I could interleave two different arrays, which would be fairly useful. But I don't see anything in the "create from source" dialog that allows this.