Ok, I'm just gonna throw this out here...POD is the survival of Henry Frederick Stuart.
HOUSE OF STUART
James I/VI Stuart, King of England, Scotland, and Ireland (b. 1566, d. 1625) m. Anne of Denmark (b. 1574, d. 1619) in 1589, had issue
1) Henry IX Frederick Stuart, King of England, Scotland, and Ireland (b. 1594, d. 1659) m. Elisabeth of Hesse-Kassel (b. 1595, d. 1647) in 1614, had issue
2) Elizabeth Stuart, Queen of Bohemia (b. 1596, d. 1662) m. Frederick V, Elector Palatine (b. ?) in 1613, had issue
3) Margaret Stuart (b. 1598, d. 1600)
4) Charles Stuart, Duke of York and Albany (b. 1600, d. 1666) m. Charlotte de La Trémoille (b. 1599, d. ?) in 1625, had issue
5) Robert Stuart, Duke of Kintyre (b. and d. 1602)
6) Mary Stuart (b. 1605, d. 1607)
7) Sophia Stuart (b. and d. 1606)
An expansion of this lineage...
James I/VI Stuart, King of England, Scotland, and Ireland (b. 1566, d. 1625) m. Anne of Denmark (b. 1574, d. 1619) in 1589, had issue
1) Henry IX Frederick Stuart, King of England, Scotland, and Ireland (b. 1594, d. 1656) m. Elisabeth of Hesse-Kassel (b. 1595, d. 1647) in 1614, had issue
1) James Stuart (b. 1616, d. 1618)
2) Robert I Stuart, King of England, Scotland, and Ireland (b. 1617) m. Elisabeth of the Palatinate (b. 1618)
3) Elizabeth Stuart (b. 1619, d. 1622)
4) Charles Stuart, Duke of Clarence and Ross (b. 1621) m. Countess Palatine Eleonora Catharina of Zweibrücken (b. 1626)
5) Anne Stuart, Queen of Sweden (b. 1623) m. Charles X Gustav of Sweden (b. 1621)
6) Maurice Stuart, Duke of Gloucester and Hamilton (b. 1625) m. Anne Hamilton, 3rd Duchess of Hamilton (b. 1632)
7) Charlotte Stuart (b. 1628, d. 1629)
2) Elizabeth Stuart, Queen of Bohemia (b. 1596, d. 1662) m. Frederick V, Elector Palatine (b. 1596, d. ?) in 1613, had issue
Issue as IOTL (so far)
3) Margaret Stuart (b. 1598, d. 1600)
4) Charles Stuart, Duke of York and Albany (b. 1600, d. ?) m. Charlotte de La Trémoille (b. 1599, d. ?) in 1625, had issue
1) Elizabeth Stuart, Princess of Orange (b. 1627) m. William II, Prince of Orange (b. 1626)
2) Charles Stuart, Duke of Cambridge (b. 1628, d. 1633)
3) James Stuart, Duke of Kendal (b. 1631, d. 1633)
4) Henry Stuart, Duke of Cambridge (b. 1634, d. 1637)
5) Charlotte Mary Stuart (b. 1636, d. 1644)
6) Edward Stuart, Duke of Cambridge (b. 1638, d. 1649)
7) Amelia Ann Sophia Stuart, Duchess of Orléans (b. 1639) m. Charles Philippe of France, Duke of Orléans (b. 1631)
5) Robert Stuart, Duke of Kintyre (b. and d. 1602)
6) Mary Stuart (b. 1605, d. 1607)
7) Sophia Stuart (b. and d. 1606)