Another daughter of Philip IV by Isabella of France surviving would be great (as she will be likely the second wife of Ferdinand III). Or we can have Philip OTL children (maybe minus Carlos II or with him dying earlier) with Margarita married to a surviving Karl Josef of Austria (aka Leopold younger half-brother) and so Leopold free for Marguerite
Anything who will keep Louis XIV away from Spain and his possessions (and the dowry of Maria Theresa much lower than OTL) can be only good
Plus anything excluding Balthasar Carlos surviving and having sons (but with him married to Mariana is unlikely so I will keep that as OTL) will likely end with Milan in possession of the Emperor
Hmm agreed, which version do you find most interesting? Another daughter for Philip and Isabella or margarita married to Karl Josef?