Zipper with 2 vehicles?

Hello, for the current occasion I would like to ask your opinion on the following incident: The vehicles A, B and C are waiting in the first position in front of the red traffic lights on a road with three lanes, which lead in the same direction – A right, B in the middle, C left. On the right lane is located shortly after the light sign system, clearly recognizable from there and signposted accordingly, a construction site, which is why only the two left lanes are continuously covered. When the LZA turns green, A, B and C reach the start of the construction site at the same time. A pushes B so far to the left that there is almost a collision between B and C. Who has to give priority to whom in this situation? §7 StVO determines in this connection: (4) If on roads with several lanes it is not possible to drive a lane continuously in one direction or ends a lane, then the vehicles that are hindered from driving further are not able to travel. (5) In all cases, a lane may only be changed if there is no risk to other road users. From paragraph 4 I conclude that Fzg. A Fzg. B has to give priority, because A can classify itself according to B on the middle lane. Do I see that right?