All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
We have already mentioned the conditions of a valid marriage contract in Fatwa 83629, so please refer to it. If you find in this Fatwa that those conditions are met, then the marriage contract is valid even if it is not registered.
If the conditions of a correct marriage contract were fulfilled and your marriage contract was valid, then you are considered the first wife of that man even if the authentication (registration) of your marriage contract was delayed until after the authentication of the marriage with the second wife. Therefore, you should not worry about this and you should feel comforted.
On the other hand, your husband should fear Allah and he must act justly between his wives since this is treating wives kindly and this is something ordained by Allah. Allah Says (what means): {And live with them in kindness. For if you dislike them perhaps you dislike a thing and Allah makes therein much good.} [Quran 4:19]
Being inclined to one of the wives is not an act of kindness. The Prophet said: “When a husband has two wives and does not act justly between them, he will come on the Day of Judgment with his body leaning to one side.” [Abu Daawood]
Furthermore, the wife has the right to ask her husband to notarize her marriage because if it is not done, it might lead to the loss of her rights and her children's rights as well. In many countries around the world, the marriage contract is not considered legal unless it is notarized. In this case, the wife or husband cannot inherit each other, the children cannot be traced back to their father and they are not considered legal heirs of their father etc., unless there are legal papers that prove it. Therefore, neglecting the authentication of the marriage contract can result in great disadvantages and the loss of many rights.
Finally, we advise you to remind your husband to act justly between his wives and among his children. Tell him that it is your right to authenticate your marriage contract in order to protect your rights. You may seek the help of the religious and influential people in regard to the above matter, and seek the help of your family members in advising him to authenticate the marriage contract with you.
Allah knows best.