The issue isn't that it's tiered, it's that it's PTPs. Stupid PTPs.

You enter each one separately. Then under other current year increases / decreases to basis, you shuffle basis back and forth so that the overall basis is with ET, and ETP, USAC, and SUN all show zero basis. You keep a side schedule, because you can't zero out the AMT basis. You curse whichever legislators allowed such things to come into being. You curse whichever salesperson sold the client the worthless thing. You cry knowing that the year of sale is going to be even worse.

Also, Lacerte won't properly suspend the PTP losses for 199A purposes. I calculate the 199A income allowed and loss carried forward in Excel, and set up a dummy K-1 (all 9s works fine for the EIN; I literally name it Dummy K-1) with a slug of 199A PTP income to get the end result right.

Those suckers are a mess.