I think that "Colgate" is, if canon, her mother or older sister. There are two similar ponies that look like Mini that often appear in a scene together. However, one of them has a white stripe in the mane, and the other one has a lavender stripe. In Cheese Sandwich's flashback, there are two Minis at the party, and one is older than the other. Minuette and Colgate are two different characters.