In this paper, we discuss the challenges that we faced during the construction of a Universal Dependencies treebank for Abaza, a polysynthetic Northwest Caucasian language. We propose an alternative to the morpheme-level annotation of polysynthetic languages introduced in Park et al. (2021). Our approach aims at reducing the number of morphological features, yet providing all the necessary information for the comprehensive representation of all the syntactic relations. Besides, we suggest to add one language-specific relation needed for annotating repetitions in spoken texts and present several solutions that aim at increasing cross-linguistic comparability of our data.