A:
The behavior you mentioned, that
your sister makes use of certain dough in hope of having children is false and groundless which must be forsaken. However, she has to rely on Allah, supplicate to Him and seek lawful medication.
And whosoever fears Allâh and keeps his duty to Him, He will make a way for him to get out (from every difficulty).
And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allâh, then He will suffice him.
Undoubtedly, having children or otherwise is something predestined by Allah (Glorified and Exalted be He). Allah (Exalted be He) said,
He bestows female (offspring) upon whom He wills, and bestows male (offspring) upon whom He wills.
Or He bestows both males and females, and He renders barren whom He wills. Verily, He is the All-Knower and is Able to do all things.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.