For the Planned orders how to create the automatic reservations?

Summary:

For Multilevel assembly components in Sales Order, back-to-back work order is created only for the top-level assembly, and for the underlying assemblies Planned orders are created in Supply Planning.

But for these Planned orders reservation in not created by the planning engine.

Content (required):

Has anyone implemented any process to automate this Reservation process.

High level overview would also be appreciated.

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Code Snippet (add any code snippets that support your topic, if applicable):