As Dr. Rapkin has stated, a high dose of raffinose given by mouth did produce diarrhea in a healthy boy. However, it would be hard to administer the same quantity of raffinose in the form of soybean formula. This is best demonstrated by the following table of the chemical composition of soybeans in weight percentage (compiled from K. Täufel et al., Zschr. Lebensmittel-Unters. und-Forschung, 112:31, 1960):
[See Table in Source Pdf.] As can be seen, stachyose and raffinose together compose about 5% of the wet weight of the beans.