Line-Up Error Causes Substitution Issue
 

Coach A indicates 7 will start on the line up. #8 reports on the court at the beginning of the set. Both #7 and #8 are on the roster.

I know the coach can use a substitute (one of the allowed 18) to have #8 start. So far, so good.

A few rotations into the set, #7 tries to substitute for #24 (a different spot in the lineup). Allowed? Reference?

I couldn't find a case on this in the book.

Number 7 cannot sub into a different position. Officially, #7 started in the position now occupied by #8, and can only sub back in to that position.

Thanks. That's how I ruled -- very confusing for the coaches (and, honestly, for me). Is there a case play? Any rule reference other than 10-3-7-c-4 (or is that sufficient)?

The only other casebook ruling that is close is 7.1.2-a which covers the original fault--i.e #7 listed on line-up but #8 is on the court. Everything else follows based on the fact that #8 substituted for #7

Correct. We aren't, by rule, "correcting" or "fixing" their lineup error; all we're doing is facilitating a substitution, 8 for 7. 7 is still in that position for the duration of the set, just like any non-exceptional substitution.