the reason for the 3 k-1's is that each entity is treated as an MLP/PTP and thus each needs to be reported separately.
The terms "master limited partnership" and "publicly traded partnership" are used interchangeably about a publicly traded company that chooses to be treated as a partnership under tax regulations. However, there are some minor differences. Not all MLPs are PTPs because some are not publicly traded (though most are).
save yourself some time in the future don't bother to enter lines that show zero. in effect, if nothing is entered on a line it is assumed to be zero.
you do not send the k-1
the most likely reason line 13K is zero is because ET has zero EBIE for the year. every one that I've seen has reported zero on that line
