  We study the dynamic geometry, loci, and invariants of three Poncelet
families associated with three distinct concentric Ellipse pairs:
with-incircle, with-circumcircle, and homothetic. Most of their properties run
parallel to those of 3 well-studied families: elliptic billiard (confocal
pair), Chapple's poristic triangles, and the Brocard porism, allowing us to
organize them in three "similar" groups.
