if partnership A receives distributions from partnerships B,C and D what goes on 19a is only what A distributes to its partners. The source of the distributions is irrelevant for this line. the distributions from B, C and D affect the basis in each of those partnerships and may or may not have their own tax implications.
from 1065 instructions
Line 19a. Distributions of cash and marketable securities. Enter on line 19a the
total distributions to each partner of cash and marketable securities
