'Periphrastic passive and perfect in old Norwegian dialects'

The project deals with the form of periphrastic passive and perfect in old Norwegian dialects. They will be discussed together, because they underwent the same process of grammaticalization, which concerned both the auxiliary and the participle/supine: an auxiliary gained respect to another one (auxiliary 'bli' respect to 'vaere' for the passive and auxiliary 'ha' respect to 'vaere' for the perfect), and the verb form of the dipendent verb (participle/supine) gained respect to the other one and could dis place this. Both processes arose around the Middle Age and affected Dano-Norwegian and New-Norwegian, but with different features: today Dano-Norwegian has passive with 'bli' and perfect tense with 'ha', using supine as non finite verb; on the opposite, N ew-Norwegian has passive in 'bli'/'verte' and perfect with 'ha'/'vaere', showing more freedom than Dano-Norwegian. Furthermore New-Norwegian uses supine with verb 'ha' and participle with verb 'bli','verte' and 'vaera', so the participle behaves like an a djective. What did happen in the past? Why does New-Norwegian show this variation and these conservative features? Nobody has discussed this topic in details up to now.