Is not asking about one's stepmother, who has a child from another man, considered a severing of kinship ties?

It is obligatory to honor one's stepmother, treat her kindly, and maintain ties with her, especially if the father requests it. Although she is not considered among the dhawat al-arham (blood relatives) whose kinship ties must be maintained for their own sake, unless there is a blood relation, not inquiring about her is considered an offense to the father and a shortcoming in maintaining ties with him. Scholars have differed in defining the precise extent of kinship (al-rahm) whose ties must be maintained. Some say it refers to those between whom marriage is forbidden. Others say it refers to those connected by inheritance. Still others say it refers to anyone with whom there is a kinship relation. The degrees of maintaining ties vary between the obligatory and the recommended, including general ties (kinship in religion) and specific ties (close relatives).