From Longman Dictionary of Contemporary Englishmuscle in phrasal verbINTERFEREto use your power to get involved in or take control of something that someone else was doing, especially in business – used to show disapproval on Banks are muscling in on the insurance business. → muscle→ See Verb table
Examples from the Corpus
muscle on• There may also be some junior males trying to muscle in on the dominant male's kingdom.• Two men were killed when members of a rival gang tried to muscle in on their territory.• I'm not going to let Jim muscle in on this deal - let him do his own negotiations. 