Charles I of Spain was at various points betrothed to a daughter of Francis I of France, however, both daughters ended up dying very young, preventing a marriage from happening.
What might've happened had one of the daughters let's say Louise who was born in 1515, had survived and lived to marry Charles and have issue?
Naturally, he doesn't marry his Portuguese cousin, preventing his children having claims to Portugal, possibly delaying the Iberian Union or removing it completely. What other consequences might this marriage bring?