First of all, tovero is extremely outdated. Yes, she will unfortunately be registered as that because the APHA sucks like that.
Second, she is a chestnut because both of her parents are chestnut. Red + red always = red.
Third, she is tobiano because she has to be with if one parent is homozygous. I don't know what her parents look like to tell you if they do, in fact, have more than one pattern. Pictures would be very helpful. A pedigree too. I can tell you though that just because her dam is registered solid does not mean that she does not carry a white pattern, it just means that the APHA did not think she showed enough white to be deemed worthy of regular papers. I would guess the filly is also splash and possibly frame.