  This is an addendum to arXiv: 0810.5376. We show, using our methods and an
auxiliary result of Bestvina-Bromberg-Fujiwara, that a finitely generated group
with infinitely many pairwise non-conjugate homomorphisms to a mapping class
group virtually acts non-trivially on an $\R$-tree, and, if it is finitely
presented, it virtually acts non-trivially on a simplicial tree
