Grafting is to have a flower that you want on a caudex you want. Growing from seeds is not the way to get a flower that you want, it's a gamble.
You absolutely cannot grow, from seed, a yellow double, or a double purple, double white, or any Adenium of specific type of flower, except pink.
The professionals know which general types have more vigorous caudexes, and sometimes they graft a slow flower to a 'fast' caudex to promote more vigorous top growth.
If you have a dozen plants, there's no reason to do grafting.
