Manchester United hope to sign Darren Fletcher's twin sons, Jack and Tyler, from City before the end of the month amid a "revenge" move by their rivals.
City are about to sign centre-back Harrison Parker, 16, from the United academy after the club refused to meet his demands for a higher salary.
United sources believe City's approach for Parker is a response to the anticipated switch of the Fletcher twins, 16, to Old Trafford.
Well-placed sources say Parker was offered a competitive financial package but the club were unwilling to break their salary structure.
Also read: United confirm 26-man squad vs Leeds
Parker joined United from the Arsenal academy in 2021 and he would have become a scholar at Old Trafford for the forthcoming season.
Parker only played three times for the Under-18s last season due to a long-term injury. Once he neared full fitness, United sensed Parker had decided to leave and figures at the club concluded he was not dedicated to the United academy.
United are comfortable with their options at centre half as Tyler Fredricson and Louis Jackson have attained England youth caps and were also involved in the triumphant FA Youth Cup run in 2022. Jack Kingdon has also played for Scotland Under-18s.
United expect to obtain a significant fee from City for Parker if an agreement is reached between the clubs or via a tribunal.
Charlie McNeill rejoined United from City for an initial £750,000 three years ago and former academy full-back Reece Devine switched from City to United in 2018.
United anticipate such deals between the country's eminent academies to become more commonplace due to the restrictions imposed by Brexit on signing teenagers aged under 18 from abroad.
Jack and Tyler Fletcher have been in the City academy for nine years but are ever-presents in the Old Trafford directors' box for United home games.
Darren Fletcher became the technical director at United in 2021, having played for the first team between 2003-15.
