I am thinking of this as an idea..
Constance duchess of Brittany m. Geoffrey Plantagenet d. 1187(a) Ranulf de Blondeville(b) Guy de Thouars(c)
1a. Eleanor(Helena), Duchess of Swabia b. 1184 m. Conrad of Swabia(Conrad III of Germany) d. 1206(a)
1a1a. Beatrix of Swabia b. 1199
1a2a. Helena of Swabia b.1200
1a3a. Frederick of Swabia b. 1202
1a4a. Gottfried of Swabia b.1203
1a5a. Isabella of Swabia b. 1205
2a. Mathilde, Queen of France b. 1185 m. Louis VIII(a)
2a1a. Mathilde of France b. 1203
2a2a. Philippe of France b. 1205
2a3a. Alienor of France b. 1207
2a4a. Louis of France b. 1210
2a5a. Constance of France b. 1212
2a6a. Jordan of France b. 1215
2a7a. Isabelle of France b. 1222
3a. Arthur I King of England and Duke of Brittany m. Sanchia of Leon(a)
3a1a. Henry III of England and I of Brittany b. 1207
3a2a. Richard, Duke of Aquitaine b. 1209
3a3a. Constance b. 1210
3a4a. Isabelle b. 1212
3a5a. Eleanor b. 1215
4c. Alix of Thouars b. 1201 m. Philippe Hurrepel of Clermont(a)
4c1a. Jean of Clermont b. 1217
4c2a. Yolande of Clermont b. 1220
4c3a. Arthur of Clermont b. 1222
5c. Guy of Thoars b. 1201 d. 1210
Constance duchess of Brittany m. Geoffrey Plantagenet d. 1187(a) Ranulf de Blondeville(b) Guy de Thouars(c)
1a. Eleanor(Helena), Duchess of Swabia b. 1184 m. Conrad of Swabia(Conrad III of Germany) d. 1206(a)
1a1a. Beatrix of Swabia b. 1199
1a2a. Helena of Swabia b.1200
1a3a. Frederick of Swabia b. 1202
1a4a. Gottfried of Swabia b.1203
1a5a. Isabella of Swabia b. 1205
2a. Mathilde, Queen of France b. 1185 m. Louis VIII(a)
2a1a. Mathilde of France b. 1203
2a2a. Philippe of France b. 1205
2a3a. Alienor of France b. 1207
2a4a. Louis of France b. 1210
2a5a. Constance of France b. 1212
2a6a. Jordan of France b. 1215
2a7a. Isabelle of France b. 1222
3a. Arthur I King of England and Duke of Brittany m. Sanchia of Leon(a)
3a1a. Henry III of England and I of Brittany b. 1207
3a2a. Richard, Duke of Aquitaine b. 1209
3a3a. Constance b. 1210
3a4a. Isabelle b. 1212
3a5a. Eleanor b. 1215
4c. Alix of Thouars b. 1201 m. Philippe Hurrepel of Clermont(a)
4c1a. Jean of Clermont b. 1217
4c2a. Yolande of Clermont b. 1220
4c3a. Arthur of Clermont b. 1222
5c. Guy of Thoars b. 1201 d. 1210