I filed bankruptcy and got a discharge. I'm now being sued in civil court for something that happened during that time. Can I reopen my bankruptcy case to include?

You should not have to re-open a bankruptcy case to "include" an omitted creditor if deadline was not established for filing proofs of claim in your case. If your case was a typical "no assets" case, no claim filing deadline would have been set.  The claim of an omitted creditor is discharged if the creditor receives notice in time to file a proof of claim.  If there is no claim filing deadline, the deadline will not have been missed, so anytime the creditor receives notice, is soon enough.  In a recent case in Indiana, In re Mathlon, the debtor wanted to reopen a case so the debtor could obtain a discharge of indebtedness owed to an omitted creditor. The Court noted that since the Chapter 7 Trustee had filed a "no asset report," the indebtedness of the omitted creditor had been discharged, because no claim filing date had ever been established in this case. Therefore the Court held that there was no need to reopen the case in discharge the debt owed to the omitted creditor, and thereof the Court would not even consider the Application to Reopen. [An exception to all of this is where the debt is based on a claim of fraud, larceny, malicious injury, etc., that could have been objected to in the bankruptcy case under sections 523(a)(2),(4) or(6).]