Numbers sharing: iCloud accounts, Mac, and PC users

I have two iCloud accounts - my main one and a separate one for my dog rescue.

I use Numbers locally on my Mac for the main database for the dog rescue - syncing to Dropbox, because the rest of the rescue stuff is stored on Dropbox. This allows me to share the database with others but it does not always sync properly and we end up getting conflicted copies. At the moment, I share the database with someone who is also on a Mac but we have two new users who are PC based so will need to access via the web version.

To keep things neat, ideally I would move it to my second, dog rescue iCloud a/c, but I don't want to keep having to toggle between profiles to do this (not least because I would be toggling all the time).

So I think the only good option is to share it via my main iCloud a/c. Unless there's a Numbers-sharing-guru who could suggest another way of doing it?