Only two premises?

Building an argument I can't make four distinct premises - it will do two and if I add a third it ads a layer to the existing premises, or makes it a co premise. How do I add more than two premises under the contention?

Just click first on a premise box in the reason or objection (you will see a blue line around it) and next give an enter; or drag a box to the right of the existing box into the reason/objection (you will see a purple vertical line).