mediate between

mediate between

To act as an intermediary negotiator between two or more people, groups, companies, countries, etc. The neutral country volunteered to mediate between the two warring nations to broker a peace treaty that would benefit both sides. Children shouldn't have to mediate between their parents—that is an unreasonable and unhealthy burden to place on them.

See also: between

Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

mediate between (someone and someone else)

to negotiate an agreement between people. I will have to mediate between Mary and Vernon. No one wants to mediate between them.

See also: between

McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.