How should one deal with the fiancée's numerous foster brothers, and is it necessary to inquire about their character before the fiancée interacts with them, taking into consideration jealousy and the fear of what people might say?

What has been mentioned does not prevent marriage to the woman if she is religious and of good character. You have the right to investigate those who were nursed with her and whether the conditions for prohibitive suckling were met for them or not. For whoever meets the conditions and his temptation is secure, there is no impediment to his entering upon her. However, if the temptation is not secure, you have the right to prevent him from entering your home.