NF rules question
 

I saw this tonight at a High School game and I wanted to know if it is correct.
Libero (#2) comes into the game for # 8 and plays the back row. When it is her turn to rotate to the left front # 8 comes back in for her. #8 then goes to the attack line and is replaced by #18. If this is allowed, why not just let #18 come in for the Libero? anyone have a case book or rules reference for this.

Are you sure this is what you saw?

What likely happened is that #8 replaced the libero, as required, then went to the substitution zone in front of the attack line where #18 subsequently substituted for #8. If this is what happened, then the procedure was correct A substitution is not the same as a replacement & they have to be handled separately. A team may have a maximum of 18 substitutions in a game, while the number of libero replacements is unlimited.

couldn't have said it better myself Tim. I really had my share in one match this year of conflicts over libero replacement conflicts. I had three different issues with libero replacements and found out later that the coach which had her stuff together had gotten away with going straight from the libero to #18 three times this year. The other coach went nuts about this exact procedure. Of course, she also said that the libero could only enter for two players and she could only replace one player in the same position. When I showed her the tracker sheet in the rulebook that she had provided she changed the subject and got yellow carded. Had I actually remembered my cards (haven't made that mistake since) by then I may have gone red+yellow!

If you mean that 18 then subbed for 8, it's because 18 cannot come on the the libero if the libero had replaced 8. Whomever the libero replaces HAS to be the one to then replace the libero. Anyone else doing it circumvents the substitution rules, and is illegal.