Marrying ones Step Mother-in-Law

Q: If a person divorces his wife and his step mother-in-law is also divorced by the father-in-law, will it permissible for the two divorcees to marry?

A: Marriage between the two divorcees is permissible.
NOTE: BY "STEP MOTHER-IN-LAW" WE MEAN A MAN'S WIFE'S STEP MOTHER, I.E. HIS FATHER-IN-LAW’S OTHER WIFE.