I agree with @Anonymous regarding the relevancy of receiving distributions from other partnerships and that it is only distributions made by your partnership to your specific partners that go on line 19a.
However, where I am not in agreement with @Anonymous is the statement that "the source of the distributions is irrelevant for this line." It may not be relevant for this line, however, there are instances where the partnership may borrow $$ and then make distributions using those dollars. This is known as debt financed distributions and this type of distribution is relevant and components of this type of distribution require special reporting.
May not apply here, but it is an important distinction. Possibly for others reading this in the future.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
