  We compare loci types and invariants across Poncelet families interscribed in
three distinct concentric Ellipse pairs: (i) ellipse-incircle, (ii)
circumcircle-inellipse, and (iii) homothetic. Their metric properties are
mostly identical to those of 3 well-studied families: elliptic billiard
(confocal pair), Chapple's poristic triangles, and the Brocard porism. We
therefore organized them in three related groups.
