Fall back in chair / fall back into chair

Question

Which is correct here back in chair or back into chair ?

Several guests noticed Mr. Edward falling back ___ his chair and gasping for breath.

We use into to emphasise on / depict the motion, since guest here saw Mr . Edward falling then we should use into, is this correct ?

Answer 1

falling back in his chair

means he was in his chair (or just sat down) and the chair fell backwards.

falling back into his chair

just means he fell backwards into a seated position in a stationary chair.

Answer 2

If he was not in the chair before he started falling back, then "fall back into the chair" would be correct.

If he was already sitting in the chair but sitting up straight or leaning forward and then "fall back in the chair" would be correct.