Alexander Firbas, Robert Ganian, Sylvain Meunier, Martin Nöllenburg. Two-Layer Drawings with a Tree on Top: Vertex Splits and Fixed-Parameter Algorithms. 34th International Symposium on Graph Drawing and Network Visualization, GD 2026, 2026, Schloss Dagstuhl - Leibniz-Zentrum für Informatik. (Note: to appear)