How to avoid order orchestration from creating supply orders

Summary:

We have a client requirement where the client is using full MRP planning. They want to enter a sales order for an ETO scenario (ship building) such that this sales order acts as a trigger for planning. Planning will further explode the BOM and determine if a work order is needed and will create a planned order for the same. They don't not want a supply order to be created by the order orchestration flow.

P.S.: They don't have a retail customer base and demand to supply hard allocation won't work for this business.

Could you please suggest on how to achieve the same from Order management side.