Other source milk means all skim milk and butterfat contained in or represented by:

(a) Receipts of fluid milk products and bulk fluid cream products from any source other than producers, handlers described in §1000.9(c) and §1135.11, or pool plants;

(b) Products (other than fluid milk products, fluid cream products, and products produced at the plant during the same month) from any source which are reprocessed, converted into, or combined with another product in the plant during the month; and

(c) Receipts of any milk product (other than a fluid milk product or a fluid cream product) for which the handler fails to establish a disposition.