Frangipanis can be propagated by seed or by cutting.
Most frangipanis are propagated by cutting in order to get a plant with the exact same flower as the parent.
Each frangipani seed will produce a unique flower using dormant and parental genes. While most flowers will be unappealing, this is the way to produce an amazing new variety. Seedlings often grow for several years before flowering so waiting to see the flower type requires patience. Growers do not usually sell seedlings since the young seedlings have an unknown flower type.