Good question! We recognize that adding users one at a time is time consuming, and we are currently investigating ways in which we can responsibly implement this feature. If you'd like to provide additional feedback, please don't hesitate to contact us at opentreemap@azavea.com.
In the meantime, you can send this registration link to your contacts via email to speed up the process:
https://www.opentreemap.org/YOUR-TREE-MAP-URL-HERE/accounts/register/
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