United States Court of Appeals For the Seventh Circuit ____________________ Nos. 19-3234, 19-3428, 19-3516, 20-1053 & 20-1503 BIG SHOULDERS CAPITAL LLC, Plaintiff-Appellee, v. SAN LUIS & RIO GRANDE RAILROAD, INC. and MT. HOOD RAIL- ROAD CO., Defendants-Appellees. APPEALS OF: SANDTON RAIL COMPANY LLC, SAN LUIS CENTRAL RAILROAD CO., RALCO LLC, SOUTH MIDDLE CREEK ROAD ASSOCIATION, THE BOARD OF COMMISSIONERS, RIO GRANDE COUNTY, RAILWORKS TRACK SERVICES, INC., and RAILWORKS SIGNALS, COMMUNICATIONS, INC., and THE AD HOC COMMITTEE OF THE UNSECURED CREDITORS and CROSS-APPEAL OF: NOVO ADVISORS and FOX ROTHSCHILD, LLP. ____________________

Appeals from the United States District Court for the Northern District of Illinois, Eastern Division. No. 19 CV 06029 — Thomas M. Durkin, Judge. ____________________ 2 Nos. 19-3234 et al.

ARGUED FEBRUARY 18, 2021 — DECIDED SEPTEMBER 3, 2021

Before BRENNAN, SCUDDER, and KIRSCH, Circuit Judges. BRENNAN, Circuit Judge. This labyrinth of appeals stems from a breach of contract claim brought by Big Shoulders Capital LLC against San Luis & Rio Grande Railroad Inc. (SLRG) and Mt. Hood Railroad Co., with federal jurisdiction ostensibly based on diversity of citizenship. In its complaint, Big Shoulders requested that the district court appoint a re- ceiver to handle SLRG’s assets. That court did so, which brought the case to the attention of the several creditors who have interests in entities in the same corporate group as SLRG and Mt. Hood. One of these parties, Sandton Rail Company LLC, intervened and challenged the appointment of the re- ceiver as well as the district court’s jurisdiction. Sandton al- leged that Big Shoulders failed to join necessary parties who, if added, would destroy diversity of citizenship. Meanwhile, other creditors—referred to here as Petition- ing Creditors—filed an involuntary bankruptcy petition on behalf of SLRG in federal bankruptcy court in Colorado. The receiver objected. Because the judicially approved receiver- ship agreement contained an anti-litigation injunction, the district court initially concluded that the bankruptcy petition was void. On reconsideration, however, the district court de- termined that it did not have authority to enjoin the bank- ruptcy. So the bankruptcy continued, and after Big Shoulders refused to continue to fund the receivership, the district court approved its termination. Out of these circumstances come several appeals. Sandton brings the main appeal which claims the district court lacked subject matter jurisdiction over the entire contract dispute Nos. 19-3234 et al. 3 because—contrary to the original pleadings—Big Shoulders, SLRG, and Mt. Hood all have Illinois citizenship. The other appeals relate to the bankruptcy petition and the district court’s decision to first enforce the anti-litigation injunction but then to allow the bankruptcy to proceed. In another layer of complexity, each appeal also involves questions of stand- ing or mootness. In the end, those justiciability questions require us to dis- miss all but Sandton’s appeal. As for Sandton’s argument that diversity jurisdiction is lacking, we remand to the district court for an application in the first instance of the “nerve cen- ter test” to determine if SLRG and Mt. Hood are citizens of Illinois. I. Background This procedural maze started with a breach of contract ac- tion, made its first turn with the appointment of receiver, banked left when the petitioning creditors filed an involun- tary bankruptcy for SLRG, and ended with the termination of the receivership. A. Breach of Contract This case began when Big