MD01N Planning Mode "Delete and Recreate Planning Data" issue

Hi Experts,

We are working on S/4HANA 1610 here the client requirement is they don't want to delete the existing planned order/Pur. req. while executing MRP Live. I have tried with planning mode 1 (Adapt Planning Data) but system deleting and recreating the planning data after each and every MRP run (Single material executed multiple MRP run). I just want to know in what condition system deleted and recreated the planning data with planning mode 1.

(The Material is planned in PPDS, MRP type-X0, ECC Strategy-40, advance planning strategy-20)

Thanks in advance