How to add discounts on both entity_level and items_level in Sales Order?

How to add discounts on both entity_level and items_level in Sales Order?

Hii,

I'm creating a sales order using API and trying to add discounts for both levels. One in items_level that is attached with line items and another in entity_level should be applied on the subtotal of line items before the tax calculation.

The issue is API is applying only entity_level discount(ignoring items_level), whereas I'm adding discount for both in the API request body. 
Is there any setting or any specific way to do so?

Thanks,