Whoa... I've learned a lot of stuff here!
I failed to mention that both are LLCs in the State of MN.
We've decided to try to get advice from a local tax prep pro (so far no luck, they are not taking on more work).
It appears that they need to close the Sole Proprietorship, dispose of inventory and surrender the EIN and apply for a new EIN for the Partnership.
Evidently, the IRS cares if it is, for example, a Sole Proprietorship, Partnership etc, for tax purposes, but not so much whether or not it is an LLC: the MN Secretary of State cares the opposite. Is this statement accurate?
I thank everyone very much for pointing me in the right direction!
