Partial or per Annotation items Synchronization possibility


I’m basically using two browsers for several reasons. Chrome and Firefox in tandem, but I do not necessarily and intentionally want to synchronize either bookmark and work what I do in the two browsers. (See: That is not necessarily the matter for me, but a use case that may be extension development for the two browsers and gathering different annotations things for that.)

After a version upgrade, one can install the extension now on Chrome unless he is registering.
However, the Firefox version is not necessarily always the same as the Chrome version.
Also, the Extensions update method is not the same for the two browsers.
E.g. I’ve been using for a long time the very early version of MEMEX for Firefox, which had not then required registration, and I’ve been upgrading that occasionally manually. Because of the continuity of the extension update, it doesn’t require registration. It is also given me the possibility in Firefox to re-install an earlier version of Memex which sometimes I use to do, due to I cannot see and read well the Dark UI, thus when some simpler functions of this extension are enough for me, e.g. using the search page I really used to switch between versions. I have also many annotations already done in Firefox in very early versions which I do not necessarily want to see in Chrome.

Recently I installed the Chrome version but that required registration and that is the most recent version, what is good for me, for example, is to see the most recent changes, having very few annotations and spaces only in Chrome yet.

I can see both Chrome and Firefox versions can work locally too even if I’m not logged in, but try to synchronize when I log in, however, the process freezes and I either log out, or I do not remember exactly how I use to cancel the synchronization.

  1. I basically do not quite understand how the synchronization process will work in this case when I log in.
    E.g. If I have more annotations made that come from an earlier of my work when the extension was allowed to work locally, and the number of annotations will exceed the counted free/month limits, what and which annotations will be uploaded and which will remain local? How does it work truly?

  2. Although I understand the common concept behind synchronization keeping the same content available across devices and browsers; As I’m saying I’m using the two Browsers for several goals, thus I do not necessarily want to see all annotations uploaded to the cloud and I also wish keeping some annotations locally only.
    However, I really want to upload coming from both browser-held annotations to a common space also kept both private and would be shared

I’m asking; Would be given the possibility to manually select which annotation be uploaded to the cloud account?