permissions

​@EmerC - Welcome to Miro!

What you are describing is not currently possible, and was actually the foundation for one of my Wish List idea posts from a few years ago (and oldie, but a goodie) for a permission type called Contributor - you can can read about and upvote it here:

https://community.miro.com/ideas/new-role-contributor-can-only-edit-their-content-10814

Other options available 

Given your statement of allowing "anyone to add whatever content they want", neither of these alternative setups will satisfy those conditions, but they might give you some ideas.

Synced Copies

If the contributors were known, and a manageable number, you could give them each their own board a frame to edit/add content to, and then add all of those frames to a main board a synced copies where they (and others) could have view-only access.

More on the Synced Copies feature here:

https://help.miro.com/hc/en-us/articles/21211471744018-Synced-copies

QR Stickies app

If you could limit content to just sticky notes, you could use the Miro QR Stickies app to allow anyone to add sticky notes from outside of the board. And, again, if the participants were known, you could even setup a QR code/frame for each person, rather than having everyone's stickies be added to the same frame. 

That's all I can think of for now, but perhaps more ideas will flow as this post grows.

HI ​@EmerC,

Robert gave a great breakdown of the current options. At the moment, Miro doesn't have a permission level that allows users to add content but not delete others' contributions. However, I encourage you to upvote the Contributor Role request https://community.miro.com/ideas/new-role-contributor-can-only-edit-their-content-10814 to help the team see the demand for this feature!

In the meantime, if your use case allows for structured contributions, the Synced Copies feature or QR Stickies app might be helpful workarounds. Let us know if you need more guidance!