Is it in any way possible or planned to add another account as a second DM to your campaign?

Asking because I'll be starting one and it would be more convenient for both DMs to have access to all information without needing to screenshare or ask the other one all the time.

There is not a way to do this—at least not currently.

What kinds of information are you wanting to share?  I ask because there may be possible workarounds/other approaches, but those depend on what you are wanting to do.

If all the PCs are public, the 2nd DM can see the other characters (except for Description section) as long as they have a character in the campaign.  They wouldn’t be able to edit those characters, though, as the campaign-making DM can.

If you mean planning notes, etc., you could use Google Docs, Dropbox Paper, or a similar service to keep shared notes. 

We're already using Google Docs and Dropbox for planning and shared notes.

As you mentioned we're lacking the ability for both of us to edit characters and view descriptions. Additionally the feature "Roll to DM", players rolling so only the DM can see, only shows for the person owning the campaign afaik.

All of these things can be worked around but it would definitely be more convenient to have a feature like this implemented.

Thanks for your reply though.

I'd say that might some day appear on the roadmap of things they would like to implement.  Sadly, I can only imagine the level of coding required to allow it would be huge, with shared permissions and all the rest.  A possible workaround for now might be to create a Co-DM account and whoever is running the show at the time uses it, to track stuff.  Likely breaches some term of use, though, which, given the reason and intent, is silly.