I'm sorry for English, I'm in Brazil and I need your help.
I work with wedding editing and I use multicam a lot. In my workflow, I cut all the cameras inside the multicam using "in, out". Then I select everything and copy it to a project at the primary level to do the assembly.
I checked that in multiclip of 10.3, I can not delete a part of the movie, using (in, out), without joining both parts, because if they join I lose the synchronization. In 10.2, I selected the part that should be deleted with (in, out), and clicked (Backspace), and with that I deleted, keeping a space between the parts. Even using the "Position" tool, this is no longer possible in 10.3.
Unfortunately in 10.3, I still can not stabilize a multicam clip. I wanted it to be possible to cut a selection and stabilize only it, but there is no way. Is this hard to do by Apple engineers or do they not care about multicam workflow?
I noticed that the multicam now opens in the same position as it was previously, in the same timecode, and that helped, because I can enter the multicam, select with "in, out", cut, stabilize and return to the primary level.
I've used "Lock and Load" previously, but I believe that before it did not stabilize multicam clips. I'm going to do a test with this new version, because this tip will help me a lot in the edition of my marriages.
On the "Shift + Backspace", it still did not work, it continues to cut the selected part and put it together, so I think it was some change they made, because in 10.2 I have here, it works normally.
I just tested the trial version of "Lock and Load", which says stabilize MC.
I have a Multicam with 4 cameras A7S2 4K. I put the "Lock and Load" in a cut part of the MC, did the trackmotion and rederizei, but the clip did not stabilize, I can enable or disable the plugin that stays the same way.
Maybe it's the 10.3.1 version I'm using. I'm going to take a test at home with 10.3.