District Judge R.H. Wallace Monday combined the suits, all of which seek compensation from Couch, 16, his parents, Fred and Tonya Couch, and the family's company, Cleburne Metal Works, and transferred the case to the 96th District Court, the Fort Worth Star-Telegram reported.
A sixth lawsuit, filed in December by the parents of a teen injured in the crash, was not included in the combined cases.
In June, Ethan Couch was driving in his pickup truck with seven teenage passengers while intoxicated. He lost control of his vehicle, causing chain-reaction collisions. Last month, he was sentenced to 10 years probation and intensive therapy by a juvenile court.
Randy Nelson, a lawyer representing Couch and his family, said he is not surprised Wallace moved to combine the lawsuits against his client.
"It makes sense to have these cases in one court," Nelson said. "If there are multiple cases involving the same incident, it is common to combine them in court for judicial economy."
Consolidating the cases will also save time for attorneys and court costs, District Judge Bill Harris said.
The lawsuits that were combined the four deaths and injuries to two teenagers, the Star-Telegram said.