ISM Policy for historical data copied from differnt source

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

2.14.0

Describe the issue:
I am copying historical data from Elasticsearch to opensearch cluster. Eventhough timestamp of the source indices are old, as indices are created as of today, its not going to warm/cold state as per ISM policy.
Inorder to do that i created separate ISM policies manually keeping allocation rule as warm

But in this case , how can i move this to cold state.

ALso this was feasible as i have only 7days of data to be moved. In PROD envirinment i have more than 30days of data in GB’s to be moved. So creating multiple ISM Policies wont workout. Can help to find a solution for this.

Configuration:

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