fwiw - i think it's to do with the wording - paternal leave v maternity/maternal leave v PARENTAL leave

paternal/paternity leave is the amount offered by your employer (in this case, three weeks paid - for my DH, it's a single week of leave). maternity leave is offered by employer as well - and generally includes the period of 6weeks post birth.

paternal leave is the period covering the first twelve months of the childs life, in which EITHER parent is able to take the time unpaid after the expiry of any paid leave. basically it's leave without pay, and only one parent can be on that type of leave at any time

please make sure you tell your employer DH gets paid PATERNITY leave, not PARENTAL leave - it should eliminate any confuzzlement!