Is it permissible for my son to marry the daughter of my wife's brother's wife, given that my wife's brother's wife breastfed her once? What are the prohibitions by reason of fosterage according to the Shafi'i school of thought? And am I sinful if I do not change my name from Muhammad Raziq to Abdul Raziq due to the difficulty of changing names in my country?

The Fatwa Summary: There is no impediment to your son marrying the daughter of the woman who breastfed your daughter, even if there was a forbidden suckling relationship between your daughter and that woman. This is because the prohibition is specific to the suckled child only and does not extend to her siblings. As for the name "Razeq," you are not required to change it, as it is not forbidden to apply it to created beings, and it is not among the names exclusively attributed to Allah the Almighty. Similarly, there is no need to change the names of deceased fathers and grandfathers, even if those names were once prohibited.