Charles' sister IOTL wed John III of Portugal, and Charles IOTL also wed a Portuguese royal, it's not exactly ASB to say Beja...there weren't exactly a lot of kings running around for five archduchesses...A match with Beja would be useleless and all the daughters of Philip and Joanna got Kings in OTLs meaning who at least a ruler is required.
Then stop to throw names just for doing it…