[BillyMac]

NFHS 9-8: A player shall not be, nor may his/her team be, in continuous control of the ball which is in his/her backcourt for 10 seconds.

"Continuous control".

NFHS 4-12: CONTROL, PLAYER AND TEAM
ART. 1 A player is in control of the ball when he/she is holding or -
dribbling a live ball. There is no player control when, during a jump ball, a
jumper catches the ball prior to the ball touching the floor or a non-jumper,
or during an interrupted dribble.
ART. 2 A team is in control of the ball:
a. When a player of the team is in control.
b. While a live ball is being passed among teammates.
c. During an interrupted dribble.
d. When a player of the team has disposal of the ball for a throw-in.
ART. 3 Team control continues until:
a. The ball is in flight during a try or tap for goal.
b. An opponent secures control.
c. The ball becomes dead.
ART. 4 While the ball remains live a loose ball always remains in
control of the team whose player last had control, unless it is a try or tap
for goal.

Situation 10 is not the same as the original post but the language is quite clear, "continuous control".

2017-18 Interpretations
SITUATION 10: A1 has the ball for an end-line throw-in in his/her backcourt. The administering official reaches a four-second count when A1 passes the ball onto the court. A1’s pass to A2, who is also in Team A’s backcourt, takes several bounces and six seconds before A2 picks up and controls the ball. RULING: Legal. Even though a team is now in control during a throw-in, the 10-second rule specifically requires that a player/team be in continuous control in its backcourt for 10 seconds for a violation to occur. Technically speaking, the thrower-in is out of bounds and not located in the backcourt. (4-35-2, 9-8)