Is the marriage contract considered legally valid if it takes place secretly without the knowledge of the wife's sister or the public, and does the ruling of divorce for non-consummation apply to the spouses in this case, and what is the minimum marital relationship that prevents this?

It is forbidden, Islamically, to establish a relationship between a man and a foreign woman, as it is a gateway to temptation and an entrance for Satan. Among the most important conditions for a valid marriage is the presence of a guardian (wali). Marriage without a guardian is not valid according to the majority of jurists. If a woman has no guardian, the Sharia (definition) judge marries her or appoints someone to marry her. If the marriage is conducted under the guardianship of a shaykh, there is no harm in that, as a concession based on the opinion of those who permitted a righteous man to marry a woman who has no guardian. It is not a condition for the validity of the marriage for the wife's sister or anyone else to know about it, and concealing the marriage from her does not make it a secret marriage that is forbidden. There is no basis in Islamic law for a wife to be divorced if her husband does not approach her for specific months. If a woman has a valid Islamic marriage contract, she becomes his wife, and he is permitted from her what is permitted for a husband from his wife, unless there is a condition or custom for delaying consummation.