You are only allowed one guest at a time on SUPs. You are responsible for rigging, transporting and stowing their board for them. You must be out on the water with your guest at all times on your own board.
You may take out guests under 19 years of age at your discretion on an SUP. Take into consideration their capabilities as well as yours in view of the weather and sea conditions, as well as your ability and confidence to assist them in the event of difficulties.