a) Filing new dependent claims (sub-claims) 

The addition of new dependent claims which do not correspond to any claims as granted is not appropriate or necessary to overcome a ground for opposition and therefore impermissible (see e.g. T 794/94, T 674/96, T 24/96). As explained in T 829/93 and T 317/90, the addition of a dependent claim is not a response to an objection that the claimed subject-matter is not patentable because it neither limits nor amends the subject-matter claimed in the relevant independent claim. The fact that dependent claims can serve as an important safety net should the corresponding independent claim ultimately be refused does not render it legitimate to add them to a remaining, broader independent claim in opposition proceedings.