any creature of more than twice the spell’s level treats the result of their check to prevent being incapacitated by the spell as one degree of success better
This means that most likely it useless in every slot but your highest. A 10th level Sorcerer certainly would not need or want it as a 2nd level spell. However, Sorcerers get very few spells, so it makes sense that you want to know the hightened version only.
You cannot swap out bloodline spells, but does this refer to the exact level of the base spell, or does it mean that you have to keep Calm Emotions in a level?
A workaround would be to make it my signature spell, but if I do not want it in 2 different levels, I certainly do not want it in all levels.
(Do not get stuck on Nymph and Calm Emotions, a Demonic Sorcerer would similarly want Fear as a 3rd level spell instead of a 1st level one)