Sounds like your NY Corp just has an investment in a Delaware partnership and would be exempt from any tax in Delaware. From Delaware code title 30: link, https://delcode.delaware.gov/title30/c019/index.html

I am not well versed in state of Delaware Corp tax, and you should do more research.

(8) Corporations whose activities within this State are confined to the maintenance and management of their intangible investments or of the intangible investments of corporations or statutory trusts or business trusts registered as investment companies under the Investment Company Act of 1940, as amended (15 U.S.C. 80a-1 et seq.) and the collection and distribution of the income from such investments or from tangible property physically located outside this State. For purposes of this paragraph (b)(8), “intangible investments” shall include, without limitation, investments in stocks, bonds, notes and other debt obligations (including debt obligations of affiliated corporations), patents, patent applications, trademarks, trade names and similar types of intangible assets;