The Parker County Sheriff's Office on Tuesday said investigators want to know if the suspects are related to any of the minors.
The Weatherford High School prom was April 28. Deputies later responded to a complaint about a party in Millsap.
Deputies say 50-year-olds Patricia Parrish Linn and Gregory Ray Wright appeared to be watching the teens drink.
Both were arrested Thursday on charges of furnishing alcohol to minors, then freed on $1,500 bonds. Online jail records did not list attorneys for them.
One boy cut his knee during the party while another suffered a dislocated shoulder. A girl hit her head falling off a ledge.