Wiktionary
a. (context idiomatic English) privy to; having knowledge of.
Usage examples of "party to".
Fallon looked around as if searching for some neutral third party to witness what was happening to him now, but there was no one.
Several of them ran biographies of the missing senator, tracing his political career from the early founding days of the National-Liberal Party to his present anti-reanimation stand.
Although he had not made up his face for school, he decided for the party to put on the full war paint of the superhuman lich.
I've ordered embassy officials and students loyal to the POPPA party to identify Granger agents working on Vishnu and Mali.
Senate in 1855, then, the following year, left the Whig party to join the newly formed Republicans.
I am sure you will contrive to get yourself and all your party to safety without any further assistance from me.
But can you really trust your boyfriend when, for instance, he is planning on having a party to which he is inviting college girls, who often smoke and seem to refer routinely to Nietzsche?
By not opposing a military coup by the great Augusto Pinochet against a Chilean Marxist, Salvador Allende, the Times implied, the United States was party to a terrorist act similar to the 9/11 attack on America.
With real effort he closed his ears to he muffled shipboard noises and distant shouts as a boat was Iropped alongside to take a boarding party to the lugger, which now rode uneasily under the frigate's lee.
Pompey and Caesar now shared the power, with no third party to serve as intermediary.