United States Court of Appeals for the Fifth Circuit United States Court of Appeals Fifth Circuit

____________ FILED January 23, 2025 No. 24-30222 Lyle W. Cayce ____________ Clerk Stephen D. Cook, Doctor; In his capacity as Co-Trustee of Marshall Heritage Foundation,

Plaintiff—Appellee,

versus Preston L. Marshall, In his capacity as Co-Trustee of Peroxisome Trust,

Defendant—Appellant, ______________________________ Stephen D. Cook, Doctor; In his capacities as Co-Trustee of The Marshall Heritage Foundation and Marshall Legacy Foundation,

Plaintiff—Appellee,

versus Preston L. Marshall, both In his official capacity as Co-Trustee of Peroxisome Trust and in his personal capacity,

Defendant—Appellant. ______________________________

Appeal from the United States District Court for the Eastern District of Louisiana USDC Nos. 2:17-CV-5368, 2:21-CV-2139 Case: 24-30222 Document: 119-1 Page: 2 Date Filed: 01/23/2025

______________________________ Before Smith, Stewart, and Duncan, Circuit Judges. Stuart Kyle Duncan, Circuit Judge: Stephen Cook, trustee of two charitable trusts, sued Preston Marshall personally and in his capacity as trustee of a related trust, alleging that Pres- ton’s lapses damaged the charitable trusts by causing them to incur debt and tax penalties. The district court denied Preston’s motion to dismiss and later granted Cook partial summary judgment. Preston asks us to dismiss the suit, among other reasons, because Cook’s unnamed co-trustees lack diversity of citizenship. We reject that argument and affirm. I. We again address litigation over the patrimony of “the late oil tycoon J. Howard Marshall.” Cook v. Marshall, 842 F. App’x 858, 860 (5th Cir. 2020) (unpublished) (“Cook I”). By way of background: Elaine Marshall, the widow of one of J. Howard Marshall’s sons, had two children: Pierce and Preston Marshall. Stephen Cook was a longtime acquaintance of the Marshall family and served as trustee on several Marshall family foundations. For decades, the Marshall family distributed large sums of money to charity through the Marshall Heritage Foundation and its predecessors. The trustees of the Marshall Heritage Foundation included Elaine, Pierce, Preston, and Cook. In 2011, Elaine created the Peroxisome Trust (Peroxisome) as a vehicle to donate $100 million to the Marshall Heritage Foundation. Peroxisome’s trust instrument made Pierce and Preston its co-trustees[.] Ibid. In 2014, the Marshall Heritage Foundation was split into two trusts: the Marshall Legacy Foundation (MLF) and The Marshall Heritage Foundation (TMHF). Ibid. In 2017, Cook (as trustee of TMHF) sued Preston, claiming Preston failed as Peroxisome co-trustee to authorize

2 Case: 24-30222 Document: 119-1 Page: 3 Date Filed: 01/23/2025

No. 24-30222

annuity payments to TMHF. Ibid. “The district court ruled in Cook’s favor, ordered Preston to authorize payments from Peroxisome to TMHF, and held Preston breached his fiduciary duties.” Ibid. We affirmed that judgment in