One thing I repeatedly find myself longing for is a method to select one piece of dynamic and then extend the selection to all linked items across players (for example to delete all of them). Ctrl+Click is quite error-prone, especially in dense scores where clicking on things more often than not selects other things as well.
(If there already exist a way to do this, like a key command, please point me in the right direction - thanks!)
To what extent can the Filter option for dynamics help you weed out the dynamics from other notation elements?
Well, when you have dynamics linked between 7 players all across a score of 30 staves, with all kinds of different dynamics going on at the same time, it is of no help at all 
And this is a quite regular use-case for me, as I’m writing for wind orchestra, where the flutes might play together with the oboe, a clarinet, a saxophone and some brass, and the players in between them are doing something completely different. When I’m at the end of the raw composing process, going on to doing some clean-up, reworking dynamics and such, selecting all linked items is an important feature I’m missing.
A command that would select the other linked friends would really be helpful to me at this step in the process.
It would be very helpful, when linking and grouping of dynamics would work independently. Often I have a group of dynamics (e. g. mf < f) from a MusicXML file, where I have to adjust the cresc. in the middle. The groups are also linked between different instruments.
At the moment I can’t select the cresc., remove it from the group, adjust it and re-group the dynamics. At the moment ungrouping unlinks the dynamics in the first step and when I press “ungroup” (or “remove from group”) again, the cresc. will be removed from the group. But now I have to repeat this for all dynamics.
It really would be great, if one could group or ungroup linked dynamics in a helpful way! (and/or be able to adjust a cresc. inside a group)