fill somebody's boots/shoes
fill (one's) boots
1. To take or obtain as much of something as one can. Primarily heard in UK. Since that store announced its going-out-of-business sale, customers have been filling their boots with formerly overpriced housewares.
2. To replace one in some role; to take over for one in some position. You do so much for the company that I don't see how anyone could fill your boots.
fill (one's) shoes
To replace one in some role; to take over for one in some position. You do so much for the company that I don't see how anyone could fill your shoes.
fill someone's shoes
Fig. to take the place of some other person and do that person's work satisfactorily. (As if you were wearing the other person's shoes.) I don't know how we'll be able to do without you. No one can fill your shoes. It'll be difficult to fill Jane's shoes. She did her job very well.
fill somebody’s ˈboots/ˈshoesdo somebody’s job in a satisfactory way when they are not there: Mr Carter is retiring and we need a new director to fill his shoes.
fill (someone's) shoes
To assume someone's position or duties.