Madeleine of Valois was the daughter of Francis I of France, and the first wife of James V of Scotland whom she married in 1537, she died later that year from a fever I believe, the marriage was without issue.
Now, what if instead of dying in 1537, she lives on alongside her husband past 1542 and has issue?
Their children:
James, Duke of Rothesay b 1538
Alexander b 1540
Margaret born 1542
Robert b 1546
What consequences could a surviving Madeleine and a surviving James V have for Scotland and England?