I have been lately wondering how to determine dynamics of individual parts in music group. As we all know sheet music many times doesn't provide all dynamics and phrasing.
It seems obvious to me, that when you have for example two parts that play the same melody in lets say thirds, dynamics must be the same. But what to do with other lines that don't play the main melody? What to do when you have two melodic lines and one or two accompaniments? Should accompaniments strictly follow all dynamics, should they just stay below the melody always at the same dynamic level or follow melodic dynamics just to some extent? What to do for example in baroque music when you have some lines that are not the main melody but also not just some "boring" chord accompaniment?
I hope that my question is not too broad. If it helps, at the moment I'm mostly interested in late baroque music (Vivaldi, Bach).
Thanks in advance!