Another thought/suggestion:

If everything runs on time you'll be fine making the 1 hour connection at DTW.

Might I suggest researching some other options. Delta will gladly put your daughter on the following days flight DTW-GRU but you may benefit from researching other options that could lessen the delay.

ie: is there a later flight to BSB or GIG where she could then connect on Gol to GRU?
is there a flight from ATL or JFK that she could connect to that same evening?
is there a flight DTW-MEX with a connection on AeroMexico to GRU?
is there time to connect DTW to any of a dozen other cities to hop an aeromexico flight to Mex and then to GRU?

If she gets to BOS and the flight to DTW is already delayed, suggest Delta proactively book her to another city to avoid the misconnect?

Delta will get your daughter to GRU, but i've found, especially with international flights, having some backups in your pocket can come in handy.