On a 1065 if the partnership received a K1 from partnership that it has an interest in. From 1065 instructions:

Domestic Partnerships

Except as provided below, every domestic partnership must file Form 1065, unless it neither receives income nor incurs any expenditures treated as deductions or credits for federal income tax purposes.

Thanks for your reply. Yes, I am aware that Form 1065 is the partnership tax return form.  However, where on Form 1065 do I report the K-1 items passed through to the partnership from the partnership it owns?  Where on Form 1065 do I report the the K-1 Box 2 net rental real estate income (loss) passed through from the owned partnership?  Same question as to K-1 Box 20 passthrough items.

It looks like the partnership reports the passed through items on Form 1065, Schedule K, Passthrough K-1s.