@BawLakshB I initially assumed that the Estimate Structure value is determined by the Part Type of the connected part of the component line (for Purchased parts). For instance, if the Part is a Purchased (Raw) type, the Estimate Structure is typically set to Disable, whereas it's set to Enable for Purchased parts (especially when there is a Purchase structure).

However, it appears that the value is only set to Enable when connecting a Manufactured part, for other parts it is set to Disable.

AFAIK, there isn't a property to control the default value of the field. Nonetheless, the application should take into account the Part Type of the connected part and then appropriately set the value of the Estimate Structure, similar to how it operates for Manufactured parts. If it is not the desired value, the user can change it later.