interpolate

verb

• insert (something) between fixed points:illustrations were interpolated in the text
• insert (words) in a book or other text, especially in order to give a false impression as to its date.
• alter (a book or text) by insertion of new material.
• interject (a remark) in a conversation: [with direct speech]:“I dare say,” interpolated her employer
• Mathematics insert (an intermediate value or term) into a series by estimating or calculating it from surrounding known values.