From Longman Dictionary of Contemporary Englishbe/get mixed up with somebodybe/get mixed up with somebodyTAKE PART/BE INVOLVEDto be involved with someone who has a bad influence on you When he left college he got mixed up with the wrong people. → mixed up
Examples from the Corpus
be/get mixed up with somebody• Then Conley got mixed up with Charlie Keating and somehow lost millions of dollars, eventually ending up bankrupt.• It's an odd business and it seems to be mixed up with Edwin Garland's will.• Of all the people you do not want to get mixed up with he is the first and the last.• Answer: She would never have got mixed up with him in the first place.• Trust Auguste to get mixed up with it.• But this all gets mixed up with motivation too: the horse must be motivated to learn.• I am beginning to get mixed up with the days of the month.• We used to get mixed up with the fight. 