The first view is that the child is attributed to him, even after ten years, because this milk originated from the husband from whom she separated and is therefore attributed to him. This is the well-known position of the madhhab, even if the husband had died or she had become irrevocably separated from him; it is also one view among the Shafi'is.
The second view is that the child is not attributed to her husband. Once the milk has ceased and then returned, how can it be attributed to him? Moreover, if she were to give birth after the separation, her child would not be attributed to him, because a child belongs to the marital bed, whereas she is no longer his wife. Thus, if lineage is not established, neither is its consequence—namely, foster-nursing. This is the apparent position of Malik's madhhab.
The third view is that if the milk returns before four complete years have passed, it is attributable to the husband; but if it returns after four years, it is not attributable to him, since the maximum duration of pregnancy is four years. Once that period has been exceeded, it is not attributed to the husband—just as, if she had borne a child, that child would not be attributed to him. This is a view within the Shafi'i madhhab.
The view closest to what is correct is that if the milk ceases and then returns after she has become irrevocably separated from him, it is not attributed to the first husband, because she has separated from him and is no longer his wife. If a child by lineage is not affiliated with the husband from whom she separated, then this milk is likewise not affiliated with him, for foster-nursing is based on lineage, as the Messenger of Allah, peace and blessings be upon him, said: “What becomes unlawful through foster-nursing is what becomes unlawful through lineage.” (1) This applies if she has not remarried.