As per the GRs, if the producer owns a GLN, it must be used in place of the GGN.
To replace the GGN with the GLN, please use the pencil icon at the producer's profile:
Replace the GGN with the GLN and click on save:
Note: The IT platform will only accept a GLN if it is
a) valid according to this algorithm
b) not already assigned to another producer
