on somebody's coat-tails

on (one's) coattails

Benefiting from someone else's success; using someone else's success as a means to achieve one's own. Everyone knows you've been on the governor's coattails these last two years, but once her term ends, you'll be on your own. A: "I can't believe Jonathan got his paper published in that prestigious journal." B: "Oh, it's only because he's on his professor's coattails."
See also: coattail, on

on somebody’s ˈcoat-tails

using the success and influence of another person to help yourself become successful: She got where she is today on her brother’s coat-tails.
See also: on