Restore snapshot into an existing datastream

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Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
2.19.2

Describe the issue:
trying to restore a backing-index to an existing datastream.

  • if I choose adding a prefix to the backing index, but keep the prefix empty, so the index restore can successful, the index name is same like other readonly backing index in the DS (the surfix number is different).
    however, this index cannot join the DS as it’s backing index.
    (i can see it via the api)

  • if give it a prefix, the index will also restore completely to be a defined prefix index.
    howerver, it still not belongs to any datastream. (it nither not creae a new DS with the prefixed name, nor adding into the exist DS).

I’m seeking a way to restore the index into an existing DS as a readonly backing-index.
so the _reindex seems not help me, because it writing the index to RW backing index in DS.

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