Let's say, instead of 14 years of barren marriage, Henry I of England and his teenaged bride Adeliza of Louvain had enjoyed the births of a few children. Let's say a son in November of 1121, Henry II of England, which clears the succession crisis and gives England a King of 14 years old at his father's death. More children follow, maybe even a daughter soon after to replace the Geoffrey/Matilda match and allow the former Empress to act as an Abbess or remarry someone more to her taste. Here's what I've come up with:
Henry I of England (b.1068: d.1135)m. Matilda of Scotland (b.1080: d.1118) (a), Adeliza of Louvain (b.1103: d.1151) (b)
1a) Euphemia of England (b.1101: d.1101)
2a) Matilda of England (b.1102: d.1167) m. Henry V, Holy Roman Emperor (b.1081: d.1125) (a)
3a) William Adelin (b.1103 : d.1120) m. Matilda of Anjou (c.1100: d.1154)
4a) Elizabeth of England (b.1104: d.1104)
5b) Henry II of England (b.1121: d.1192) m. Constance of France (b.1124: d.1176) (a)
1a) Matilda of England (b.1149)
2a) Stephen II of England (b.1151)
3a) Euphemia of England (b.1155: d.1165)
4a) John of England (b.1157)
5a) Henry of England (b.1160: d.1160)
6a) Laura of England (b.1161)
7a) William of England (b.1164: d.1164)
6b) Adela of England (b.1123: d.1189) m. Geoffrey Plantagenet, Count of Anjou (b.1113: d.1151) (a)
1a) Henry Plantagenet, Count of Anjou (b.1129)
2a) Sybilla Plantagenet (b.1132)
3a) William Plantagenet, Count of Nantes (b.1134)
4a) Geoffrey Plantagenet, Viscount of Dieppe (b.1136: d.1152)
5a) Adeliza Plantagenet (b.1140)
6a) Euphemia Plantagenet (b.1140: d.1140)
7b) Stephen of England (b.1124: d.1132)
8b) Joan of England (b.1126: d.1126)
9b) Emma of England (b.1129: d.1150) m. Eustace IV, Count of Boulogne (b.1127: d.1153) (a)