Director, Rob Marshall said that the Oscar-winning actress, whom he worked with in "Into the Woods", was drawn to his 2018 movie because of its message of optimism, reported Entertainment Weekly.
In the movie, Topsy receives a visit from the nanny (Emily Blunt) and the Banks children during their adventurous lessons.
Streep also gets her own song, penned by Marc Shaiman and Scott Wittman, when she welcomes her young guests to her world, which is lived almost entirely in upside-downs and opposites.
The sequel to the 1964 classic also stars Lin-Manuel Miranda, Dick Van Dyke, Emily Mortimer, Ben Whishaw and Angela Lansbury.