How to merge passive losses in MLP merger?

In 2018 I owned two oil and gas  Master Limited Partnerships (ETE and ETP).  Both are publicly traded.  During 2018 they merged into a new entity ET.  I have checked the "Final K-1" in for ETE and ETP.  Do I also check the "Partnership discontinued during 2018" box or one of the other choices?  And more importantly, how to I get my deferred passive losses moved from ETE and ETP over to ET?