I was updating the NOM database and noticed that Leyenda del Milagro now has its own distillery listing and NOM:

Tequilera Milagro, S.A. de C.V.
NOM 1559

They were building quite a bit when we visited last spring, so I'm not sure if they are still part of Industrializadora de Agave San Isidro and just in a separate building, or if they broke off into an entirely new distillery and location.