Second, it is all about evidence. Make sure your daughter prepare witness contact, medical information in a very organized fashion.
Here is what is likely to happen. (For your reference only, please get a lawyer.
1. Criminal prosecution:
Your daughter will go to police department to report being assaulted by her BF in the same event. A detective will interview your daughter and collect all the evidences. Make sure give him the medical records, witness contacts etc. Also the fact that DA already have a case on the same event. The dectective will pass the information to same DA.
Have your lawyer talk to the DA on these information, the DA might decide to drop the case against your daughter in view of these new information, or chose to prosecute both your daughter and your daughter's bf. Because DA is in charge of the crimincal case, civil litigation is not going to affect DA's decision. From what you said, I think it is likely DA is going to drop the case.
Worst outcome, if convicted there probably won't be any jail sentence, maybe just anger management class. But there will be a conviction on record which is not ideal.
2. Civil side:
All civil case on the same event cannot proceed before the criminal case, because the defedant cannot testify in civil case without incriminate him/herself in the criminal case. Your lawyer will ask for a stay (delay) of civil case until the criminal case is over (or dropped).
In the BF's civil case against your daughter, your lawyer will file a counterclaim against the BF for assault and battery.
Wait until criminal case is over. Depend on the result of criminal case, there might be a chance to resolve the civil case privately.
Then the civil court will hear the BF's case and the counterclaim TOGETHER. Again, evidence will win your case, so make sure your daughter have everything together.