How different is the arrival/unlocking of Sinon and Leafa in Hollow Fragment when compared to Infinity Moment?

When I played Sword Art Online: Infinity Moment, Leafa and Sinon where nowhere to be seen in Floor 76 and no indication was given to how or when they will become available. On Sword Art Online: Hollow Fragment, both of them are unlocked from the start of the game after finishing the Hollow Area Tutorial.

How different is the arrival/unlocking of Sinon and Leafa on Infinity Moment when compared to Hollow Fragment? How were you able to unlock them in the original game?

The "Do you want to think back on what happened in Aincrad?" cutscene shows that Leafa

was found in a forest

and Sinon

fell from the sky in floor 76

But that raises more questions like

In what floor was Leafa originally found

and

From what floor did Sinon fell down in Infinity Moment