I think it’s best to follow whatever instructions you can get from the help resources provided by the company. Do a Google search for “etp mlp k1” and you’ll get to a page with a phone number for help and other resources.
A Schedule K-1 reports income from pass-through entities — which are partnerships, S corporations, estates, trusts, and LLCs. If you’re a member of any of these, you’ll likely receive a K-1. Watch this TurboTax Support video for guidance on using Schedule K-1 to accurately file your taxes.