The present article concerns parenthesis-adverbial discourse-text 'transitions'. These elements present a complex phenomenon, having numerous subtypes and various functional- semantic manifestations in modern English. Existing at the junction of auxiliary and full- semantic units systems, parenthesis linking words show a tendency for interaction in terms of integration/differentiation with so called 'pure' copulas ' primary bearers of conjunction category semantics. Dwelling upon the main factors and prospects of this multi-aspect process, the authors give a detailed picture of its consecutive stages. The results of original practical material complex analysis carried out in the frame of given research allows to state a large functional scope of most discourse-text parenthesis-modal 'transitions', possessing hybrid lexical-grammar manifestations, high transposition abilities and a strong transformation potential. The frequency of the different types of 'transitions' used as sentential and inter-sentential connectors in modern English considerably depends on discourse-text units structural- compositional, stylistic and genre particularities.