be party to something
be (a) party to (something)
To be involved in something, often something clandestine. I refuse to be a party to your schemes any longer!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
be (a) ˈparty to something(formal) take part in a (secret) plan, agreement, etc., and therefore be partly responsible for it: ‘Were you a party to this, Anna?’ ‘No, Mrs Jones, I was away on holiday at the time.’ ♢ How many people were party to the plan?
Farlex Partner Idioms Dictionary © Farlex 2017