INTERPOLATE

to interject

estimate the value of
SYN - extrapolate

insert words into texts, often falsifying it thereby
SYN - alter, falsify

"He had hoped to interpolate these damaging words into the speech."

"Nietzsche suffered from her sister interpolating his unfinished works."

"He had to make sure that whatever from this point to the final print no-one especially not bobby, would be able to interpolate his work."

"He had asked if it would be okay if he could interpolate a few words between the two bands performances."