  Chiral-antichiral pairs of non-Abelian Hall states, like the Pfaffian,
Read-Rezayi and NASS states, can be used to model two-dimensional time-reversal
invariant topological insulators. Their stability was shown to be associated to
the presence of a Z_2 anomaly and characterized by the same Z_2 index
introduced for free fermion and Abelian systems. In this work, we continue the
stability analysis by providing the form of time-reversal invariant
interactions that gap the non-Abelian edge excitations. Our approach is based
on the description of non-Abelian states as projections of corresponding
"parent" Abelian states.
