We present an ongoing project of enriching an annotation of a parallel dependency treebank, namely the Prague Czech-English Dependency Treebank, with verb-centered semantic annotation using a bilingual synonym verb class lexicon, CzEngClass. This lexicon, in turn, links the predicate occurrences in the corpus to various external lexicons, such as FrameNet, VerbNet, PropBank frame files, OntoNotes, and WordNet. We briefly describe the content of the CzEngClass synonym class lexicon and then we focus on its use for an enrichment of corpus annotation, which proceeds in two steps -automatic preprocessing and manual correction. This paper describes a first milestone of a long-term project; so far, approx. 100 CzEngClass classes, containing about 1800 different verbs each for both Czech and English, are available for such annotation. The corpus coverage at the moment is about 50%, allowing us to extract some basic statistics and discover a set of issues that appeared during the annotation process. The ultimate goal is to have a high-coverage, multilingual verbal synonym lexicon and corpora with all events annotated by such lexicon, to serve both theoretical studies in lexical semantic, translatology, corpus annotation studies etc. as well as a usable resource for training automatic semantic text processing systems for event/participant detection and linking and for general information extraction.