Just a little remark: even if Snow and Charming and Thomas and Cinderella aren’t yet King&Queen, their daughters Emma and Alexandra are princesses. They automatically are, because at least one of their parents (or both actually) is a prince/princess.
Real life examples:
The infantas are princesses, even though Prince Felipe is not yet king. Prince William and Prince Harry are princes even though their father isn’t yet king. The princesses of The Netherlands, Denmark and Sweden also, etc. 😉
True in both cases. Remember, not that it really matters but Emma was born as the curse was coming. Alexandra was not born until Cindy/ashley was in Storybrooke. Yes they are both Princesses. Thomas was also missing after the capture of Rumple.