Barbara von Erlach (nee de Praroman of Freiburg) with daughters modeled (see image to the very bottom right, from the Spiez Shilling). Barbara was the wife of Altschultheiss Rudolf von Erlach, the patron of the Berner Schilling.
I think this is a kirtle rather than a chemise revealed when she pulls off the overgrown, the fabric underneath is really beautiful! A woman undressing before entering the fountain of youth. From a fresco, circa in the great hall of the Castello di Manta.