WEATHERFORD-April 15, 1999 A Parker County grand jury returned four separate indictments Thursday charging a Fort Worth man with intoxication manslaughter in the Dec. 19 deaths of four Brock High School students.  Killed in the wreck were Stacey Lee, 16, Mandi McWhorter, 15, and Whitney Welch,16. A fourth occupant, Lacey Osina, 17, died Dec. 22 in a Fort Worth hospital.  Rickey Carter, 40, drove a pickup that collided head-on with the teen-ager's on Spur 312 about a mile west of Weatherford. His alcohol blood level tested .016.  Driver of the Nissan Maxima was Lee who was alcohol free. All four girls wore seat belts, officials said.  Intoxication manslaughter is a second degree felony carrying a possible penalty of two to 20 years in prison and up to a $10,000 fine.  The girls were making their way home on a two-lane roadway after a taco dinner and renting holiday movies in Weatherford. Department of Public Safety investigators said the girls were traveling slightly under the speed limit while the speedometer on Carter's pickup was frozen on 83 mph.  The indictments are a step in the right direction, said Leslie McWhorter, mother of Mandi.  "This is one of many hurdles that we're going to have to face. We're glad we are passed that. Now trial dates will be set and we definitely want to see it go to trial,'' McWhorter said.  The tiny Brock community is still suffering from the loss but does not wear a long face, said Brock school superintendent Clead Cheek.   "The emotions are still just below the surface. The kids are handling it one day at a time, one step at a time. This is one of the most difficult things I've ever done in the 20 years I've been a superintendent...the whole thing has taken on a dynamic of its own,'' Cheek said.  "The girls that got killed were happy kids. Of course, their memory leaves a big hole in the community but when you remember those kids, you can't sit around with a dour face because those kids weren't that kind,'' Cheek said.  Impact from the deaths has been far-reaching and contributions for scholarships in the girls' memories stands at $42,000 to $48,000, Cheek said.  "I've had calls from guys I've known in the school business from all over the State of Texas. It's been recognized by the school communities. I've heard from superintendents all over Texas,'' he said.  Cheek said he could not comment on Carter's indictments.