Answer: interpolating

AnswerCrossword Clue
interpolatingINTERPOLATE, to insert a word or passage in a book or manuscript, esp in order to mislead
interpolatingInsert (something) between fixed points
interpolatingInsert (an intermediate value or term) into a series by estimating or calculating it from surrounding known values
interpolatingMake such insertions in (a book or text)
interpolatingInterject (a remark) in a conversation
interpolatingInsert (words) in a book or other text, esp. in order to give a false impression as to its date