nitpicker- The “famous story” is probably the one that is in Igros Moshe.
Dr. Seuss- A girl under bat mitzvah can be married off by her father min haTorah and by her mother/brother mDirabannan.
2qwerty- As far as I know there is no kiddushin without eidim. (other than possibly a shtar written in his handwriting that she has in her possession)
mommamia22- That is part of the question. Generally we say “D’varim Shebilev Lo Havi Devarim” loosely translated as intent which contradicts the actions that we see are not taken into consideration.