Add SSH key management instructions for multiple accounts (#59664)

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: erichanson1

content/account-and-profile/how-tos/account-management/managing-multiple-accounts.md

@@ -101,6 +101,57 @@ For example, the following command sets the `GIT_SSH_COMMAND` environment variab
 GIT_SSH_COMMAND='ssh -i PATH/TO/KEY/FILE -o IdentitiesOnly=yes' git clone git@github.com:OWNER/REPOSITORY
 ```
 
+## Contributing to multiple accounts using SSH and multiple keys
+
+If you are a member of an {% data variables.enterprise.prodname_emu_enterprise %}, but also want to collaborate outside your enterprise using a personal account, you can use different SSH keys for each account. For more information about using SSH, see [AUTOTITLE](/authentication/connecting-to-github-with-ssh).
+> [!WARNING]
+> You cannot use the same SSH key to contribute to both repositories inside your {% data variables.enterprise.prodname_emu_org %} and outside the enterprise. 
+
+1. Generate a different SSH key for the repositories in your {% data variables.enterprise.prodname_emu_org %}. See [AUTOTITLE](/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent#generating-a-new-ssh-key). When you save the key, give it a different filename from your existing key (for instance, add -emu to the suggested name of the file).
+
+1. Add the new ssh key to your {% data variables.enterprise.prodname_managed_user %}. See [AUTOTITLE](/authentication/connecting-to-github-with-ssh/adding-a-new-ssh-key-to-your-github-account#adding-a-new-ssh-key-to-your-account)
+
+1. Configure your SSH Config File `~/.ssh/config` to use the different keys. For example, if your personal SSH key is `~/.ssh/id_ed25519` and your {% data variables.enterprise.prodname_emu_enterprise %} SSH key is `~/.ssh/id_ed25519-emu`
+
+   ```text copy
+   Host github.com
+	   IdentityFile ~/.ssh/id_ed25519
+       IdentitiesOnly yes
+
+   Host github-emu.com
+	   Hostname github.com
+	   IdentityFile ~/.ssh/id_ed25519-emu
+       IdentitiesOnly yes
+   ```
+
+   > [!NOTE]
+   > The `IdentitiesOnly` line ensures that if the ssh-agent has loaded multiple keys, ssh uses the correct key when connecting.
+
+1. Test your SSH configuration by running the following command to connect using the SSH key associated with your personal account - see [AUTOTITLE](/authentication/connecting-to-github-with-ssh/testing-your-ssh-connection) for further details
+
+   ```shell copy
+   ssh -T git@github.com
+   ```
+
+   Test to see if you can connect to ({% data variables.product.github %}) using your {% data variables.enterprise.prodname_emu_enterprise %} SSH key
+
+   ```shell copy
+   ssh -T git@github-emu.com
+   ```
+
+1. Tell `git` to use the correct key when downloading or uploading a repository in an {% data variables.enterprise.prodname_emu_org %}. 
+   To list the organizations in your {% data variables.enterprise.prodname_emu_enterprise %},
+   {% data reusables.profile.access_org %}
+   1. For each organization listed tell `git` to use the `github-emu.com` host.
+
+   For example, if one of your organizations is called `octocat-emu` then to tell `git` to use the host `github-emu.com` for repositories in the `octocat-emu` organization, run the following command
+
+   ```shell copy
+   git config --global url."git@github-emu.com:octocat-emu/".insteadOf "git@github.com:octocat-emu/"
+   ```
+
+Now, when you clone a repository using SSH, in the `octocat-emu` organization, `git` will use the SSH key associated with your {% data variables.enterprise.prodname_emu_enterprise %} instead of your personal key.
+
 ## Next steps
 
 For reference information, see [AUTOTITLE](/account-and-profile/reference/personal-account-reference).