My friend Fr. Jay Finelli let me know a while ago that Bishop of Worcester has granted canonical status to the Slaves of the Immaculate Heart of Mary in Still River, MA. He has this on his site:
Congratulations to my dear friends, The Slaves of the Immaculate Heart of Mary in Still River, Massachusetts. On 27 October, the Most Rev. Robert J. McManus granted them canonical status as a Public Association of the Faithful. Check out the decree below.