Yes, you can edit the recipients of a packet after it has been uploaded.
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First, find the package in your Sent Packages list.
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To remove access to a package for a user, find them in the recipients list and select the additional actions menu at the end of their row (this is an icon with 3 vertical dots). Select 'Remove Access'. This will immediately prevent the user from being able to download the package and if the access window has yet to start they will not receive the package notification

You can add users to a package using the 'Add Recipients' button. This gives you the ability to add multiple new recipients and send a new message if desired.

Note: Adding new recipients does not extend the package storage time. Make sure any newly added recipients have time to download the package before it expires.
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