What is the ruling regarding children who were not breastfed by their mother, whether they were born before the four whom she breastfed or after them?

Lactation prohibits what lineage prohibits, based on the Messenger of Allah's (peace and blessings be upon him) saying: "Lactation prohibits what lineage prohibits." The nursing woman is treated as the mother, and everyone who is prohibited to a son through his mother by lineage is also prohibited through the nursing mother. Therefore, the nursing woman became a mother to the four children who nursed from her, and her children are their siblings, whether born before or after. As for the siblings of the children whom she did not nurse, they are strangers to her, because lactation is a cause, not a lineage.