Or flanker binds to the shorts of the second row (but still on the outside), rather than the shoulders, making himself the rear-most players, and still legally bound as well. Nothing says they have to be shoulder to prop. And at that age, the flankers generally aren’t really helping with the scrum.
I understood at U19 scrums had to be 3-4-1 and symmetrical.
[LAWS]LAW 20: SCRUM
20.1 (f)
In an 8 person scrum the formation must be 3-4-1, with the single player (normally the Number 8) shoving on the 2 locks. The locks must pack with their heads on either side of the hooker.
Exception: A team must have fewer than eight players in its scrum when the team cannot field eight suitably trained players in its scrum due to either the team not fielding a complete team, or a forward player being sent off or temporarily suspended for foul play, or a forward player leaving the field because of injury.
Even allowing for this exception, each team must always have at least five players in a scrum.
If a team is incomplete and it cannot field eight suitably trained players in its scrum, the scrum formation must be as follows:
If a team is without one forward player, then both teams must use a 3-4 formation (i.e. no No.8).
If a team is without two forward players, then both teams must use a 3-2-1 formation (i.e. no flankers).
If a team is without three forward players, then both teams must use a 3-2 formation (i.e. only front rows and locks).
When a normal scrum takes place, the players in the three front row positions and the two lock positions must have been suitably trained for these positions.
If a team cannot field such suitably trained players because:
either they are not available, or
a player in one of those five positions is injured or
has been sent off for Foul Play and no suitably trained replacement is available, then the referee must order uncontested scrums.
In an uncontested scrum, the teams do not compete for the ball. The team putting in the ball must win it. Neither team is allowed to push the other team away from the mark.[/LAWS]