If you are using shared folders in GroupWise, it’s important to note that sharing works differently in Gmail. Gmail relies on labels instead of folders, but they work in a similar way. Unfortunately, there is no way to simply share a single label or set of labels with other Gmail users. It is possible, however, to use Gmail Account Delegation to share email and associated labels with other users. Learn more about Gmail Account Delegation here https://support.google.com/mail/answer/138350?hl=en.
One disadvantage of Gmail’s Account Delegation feature is that the users with delegated access to your account are granted full access to all of the email and contacts in your Gmail account, and access cannot be limited to a single label or selected set of labels. Additionally, there is no “read-only” option in Gmail, so users with delegated access can send and delete email in your account.
If you are using shared folders in your GroupWise account, you may want to consider creating a new Gmail resource account for some (or all) of those shared folders. Then, use Google’s Account Delegation to grant other users access to the new resource.
Please contact the Gmail Migration Team if you are interested in converting a shared folder to a resource account so you can share access to those messages with other Gmail use