OP-

to you and your daughter. I'm a teacher, and I hate this crap.
My school is K-6, and we have a "Bully Box" in the office where kids can report bullies who are bothering them, or if they have seen another student being bullied. Might be a good suggestion for your school.
There are new bullying laws (I think state wide for us)...we had to review them with all of the students. What those other students have done to your daughter (the names, causing her grades to suffer) would DEFINITELY be considered bullying by the definition in the law.
Here's the deal...your daughter DOES NOT and SHOULD NOT have to deal with any of this garbage. Yes, kids can be mean...but they can also be taught how to be kind and compassionate. I always tell my students that they are never allowed to make another student not want to come to school. That every kid has the right to come to a school that is a positive place where they can do their best to learn and be successful.
I would start with your daughter's teachers. If any snide comments are happening in the classroom, the teachers can be on the lookout and catch them offenders without your daughter "snitching." Here's an example...I teach 6th graders (music) and if I caught a student making rude comments (and knew there was a pattern of behavior), I would ensure that the student lost his/her chance to walk with the rest of the students between classes, and would have to wait for an adult "chaperone" because they were not mature enough to be respectful to the other students. If the problem continued, I would have the parent on the phone that night, and administration involved.
Bullying should not be tolerated...EVER. Yes, a kid can goof up and say a mean thing,
(In 4th grade music class this week: Kelly, why did you call Adrianna a pig? Kelly: Because she looks like a pig, her nose is kind of big.)
Learn why it was disrespectful, apologize, and move on. But when there is a group of kids involved, and the behavior is repeated...it's time for it to stop.
OP, good luck! If you end up with more problems, seriously check out the bullying laws in your area! I'm not saying to go there now, but it's good to know that they are there if you need them!