fill someone's shoes

/F IH1 L S AH0 M W AH0 N EH0 S SH UW0 Z/
verb
  1. 1

    To do (somebody's) job; to perform or assume (somebody's) role.

    โ€œI don't think anyone could ever fill her shoes, doing all she does.โ€

Source: https://en.wiktionary.org/wiki/fill%20someone's%20shoes