How to Update existing ITEM_GID and GTM_STRUCTURE_GID values to a new sequence (GTM)

Summary:

Additional Details:
1) New Sequence also would be determined outside GTM. We will have a mapping of existing id to new id.

2) Please Help with below:

 -> How the old-new id mapping should be input to GTM.

-> Share the scripts needed for update, steps to execute and validate.

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