Sex position how to convince girl twins?

Position no help. Despite all the tales out there, there is no one "position" that will help you conceive either girls or twins. Twin gestation is dependent upon ovulating 2 eggs, and that happens days before you are in any "position" to conceive. Likewise, no position favors male or female sperm making it to those eggs. Be happy with whatever children you are blessed with and just enjoy whatever "position".