Cheecking in online with an infant

My husband, infant and i were travelling to Durban on MN603 at 17.15 on Friday, 13 Feb 2015. Since we were travelling with an infant, we cannot check in online. The agent behind the counter proceeded to place my family in two different seats. When we queried this and asked to be put together, the agent said that there were no seats available and that we should have checked in online. Needless to say, we called the Manager and he said that it IS possible to cehck in online with an infant, as Kulula's IT dept sorted out the 'issue' they were experiencing. He also said that it does not matter which side of the plane you sit on, there are extra masks on both sides of the plane (contrary to what call centre agents tell us - infants must be seated on the left side of the plane due to the additional mask). We ended up sitting on the RHS of the plane to Durban. The Manager also proceeded to tell us that we should have checked in online as the system is working. I would like to know if it is safe to be seated on the RHS of a plane with an infant. I would also recommend that travellers with infants be preseated at least, to avoid being seated in differnet ends of the plane.