Starlight Glimmer and Starswirl's spells

First she used cutiemark-affecting spell. And we all remember the unfinished Starswirl's masterpiece that messed with cutiemarks and then provoked Twilight's ascension. Now she used Starswirl's time-travel spell, modified by herself. Maybe cutiemark-steal spell was also modified Starswirl's? And, also, I suspect that the source of all this Starswirl's spells in her hooves is not Canterlot Library. I think she's Starswirl's descendant, and have his personal archive. Also, her heredity explains her exceptional magical talent - she's even stronger than Twilight, Princess of Magic!