Sigismund I the Old (1467 - 1548), m. 1512 Barbara Zapolya (1495 - 1515) (a), m. 1517 Bona Sforza (1494 – 1557) (b):
- a) Hedwig (1513 - 1573), m. 1535 Joachim II Hector of Brandenburg (1505 - 1571)
- Elisabeth Magdalena (1537 - 1595)
- Sigismund, Archbishop of Magdeburg
- Hedwig (1540 - 1602), m. 1560 Julius of Brunswick-Luneburg
- Sophia (1541 - 1564), m. William of Rosenberg
- Joachim (1543 - 1544)
- a) Anna (1515 - 1520)
- b) Isabella (1519 - 1559), m. 1539 John Zapolya (1490/91 - 1540)
- John Sigismund Zapolya (1540 - 1571)
- b) Sigismund II Augustus (1520 - 1572), m. 1543 Elisabeth of Austria (1526 - 1545), m. 1549 Catherine of Austria (1533 - 1572)
- b) Sophia (1522 - 1575), m. 1542 Charles Victor of Brunswick-Luneburg (1525 – 1553)
- Charles Sigismund of Brunswick-Luneburg (1542 - 1545)
- Henry VI Victor of Brunswick-Luneburg (1545 - 1620)
- William of Brunswick-Luneburg (1548 - 1605)
- Sophia of Brunswick-Luneburg (1551 - 1621)
- Mary of Brunswick-Luneburg (1553 - 1556)
- b) Anna (1523 - 1596), m. 1548 John Albert I of Mecklenburg (1525 - 1576)
- Isabella of Mecklenburg (1548 - 1557)
- Anna of Mecklenburg (1550 - 1620)
- Albert of Mecklenburg (1552 - 1557)
- John VII of Mecklenburg (1555 - 1615)
- b) Catherine Jagiellonica (1526 - 1583), m. 1548 Augustus I of Saxony (1526 - 1586)
- John Sigismund of Saxony (1548 - 1549)
- Eleonore of Saxony (1551 - 1616)
- Elizabeth of Saxony (1554 - 1555)
- Mary of Saxony (1557 - 1629)
- Augustus of Saxony (1560 - 1619)
- Anna of Saxony (1562 - 1604)
- Catherine of Saxony (1564 - 1626)
- Casimir of Saxony (1567 - 1568)
- Amalie of Saxony (1573 - 1583)
- b) Albert Jagiellon (1528 - 1593), m. 1549 Anna d'Este (1531 - 1607):
- Anna (1551 - 1601), m. 1565 John III of Sweden (1537 - 1592)
- Sigismund III Casimir (1555 - 1622), m. 1570 Elisabeth of Austria (1554 – 1592) [1]
- Sophia (1558 - 1607), m. 1572 Charles IX of France (1550 - 1574)
- Alexander Nicholas Jagiellon of Bari (1562 - 1632), m ? Margaret Farnese of Parma (1567 – 1643)
- Hedwig (1564 - 1604), m. 1585 John William of Julich-Cleves-Berg (1562 – 1609)
- Elisabeth (1567 - 1633), m. ? Henry II of Lorraine (1563 – 1624) [2]
- Catherine (1570 - 1636), m ? Maximilian I of Bavaria (1573 - 1651)
- b) Barbara (1531 - 1594), m. 1546 Ferdinand II of Austria (1529 - 1595)
- Ferdinand (1546 - 1588) (*)
- Mary (1549 - 1610)
- Charles (1552 - 1617)
- Andrew (1554 - 1555)
- Rudolf (1556 - 1557)
- b) Alexandra (1533 - 1575), m. 1557 Philibert of Baden-Baden (1536 - 1569) [3]
- Maria (1558 - 1559)
- Anna (1560 - 1622)
- Jakobea (1562 - 1566)
- Louise (1566 - 1567)
- Alexandra (1568 - 1646)
After long: an update on the tree! Now for more matchmaking I will need help.
Plausibility check on Ferdinand (*) marrying Claude of Valois? If so who would take up the vacancy for Charles III of Lorraine's marriage?
[1] It occured to me that after Elisabeth's death Sigismund would likely remarry.
[2] Marriage shown in italics since Ferdinand marrying Claude would butterfly OTL's Henry out of existance.
[3] Funnily enough TTL's Philibert having only daughters wouldn't change too much down the line for Baden.
Edit: Credit where credit is due, random children generated via mcdemarco's Random Family Tree Generator 3.1.