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Login to your Pantheon Dashboard
Open Click the Multidev tab
Click the Create an Environment button
On the Create Multidev Environment modal that pops up, Name the New Environment and Git Branch and under the Cone Database and Files From: drop-down select a database.
Click the Create Environment button
Wait
Once it is done you will see:
Click the name of your Multidev to open its dashboard
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Click the Clone with Git button
Click the Show Detailed Instructions link
Follow the Example for your changes
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