In re Marriage of McAllister, 2021 IL App (5th) 210122-U

- Case citation and parties
In re Marriage of McAllister, 2021 IL App (5th) 210122‑U. Petitioner‑Appellee: Angelica Martinez McCallister; Respondent‑Appellant: Amanda Rowen McCallister. Intervenors‑Appellants: Charla and Steven Finn (Amanda’s parents).

- Key legal issues
1) Whether the trial court’s modification of medical decision‑making (from Amanda’s asserted sole authority toward joint decision‑making with Angelica) was against the manifest weight of the evidence.
2) Whether the Finns (grandparents named in the parenting plan but not signatories) were entitled to intervene to defend their allotted parenting time.

- Holding/outcome
The Fifth District affirmed. The modification of medical decision‑making was not against the manifest weight of the evidence. The trial court did not err in denying the Finns’ petition for leave to intervene.

- Significant legal reasoning (summary)
• Evidence: Trial testimony and expert evaluations (notably custody evaluator Dr. Clipper and neuropsychologist Dr. Dyer) supported the trial court’s finding that joint medical decision‑making better served the children’s best interests. The evaluator recommended shared responsibility to reduce conflict, allow both parents constructive participation, and avoid repeated court involvement; Dr. Dyer did not find equal parenting time per se inappropriate. Testimony also established that Amanda had at times exercised sole authority in ways that limited Angelica’s participation. The appellate court deferred to the trial court’s credibility determinations and factual findings and concluded the record supported modification.
• Intervention: The parenting plan expressly awarded “grandparents” non‑prejudicial, revocable time and the Finns were not signatories; they did not assert a separate statutory right to visitation (750 ILCS 5/602.9) or show a separate legal interest adequate to intervene. The trial court’s written denial was affirmed — the court found the plan’s plain language reflected the parties’ intent and did not err in denying intervention.

- Practice implications for family law attorneys
• Draft parenting plans with clear language about third‑party (grandparent) rights, including whether such rights are intended to be contractual/irrevocable or contingent and whether third parties will be signatories.
• If representing third parties seeking intervention, timely assert a statutory basis (e.g., 750 ILCS 5/602.9) or demonstrate a cognizable, protectable interest beyond a contractual allocation in a parenting plan.
• In disputes over medical decision‑making, develop a record on best‑interest factors and co‑parenting dynamics (use custody evaluators, treating providers, and concrete examples of exclusion or cooperation). Appellate courts will defer to trial credibility and manifest‑weight review.