Is it permissible to marry a married man without a legal contract, given his wife's refusal to return to Morocco or to allow him to marry another, even with the family's consent and public declaration?

If the marriage is conducted with an offer from the guardian and acceptance from the husband, and in the presence of two just witnesses, then the contract is valid and complete. It is not a condition for it to be done before a judge or a marriage officiant, or to be officially registered. Nor is it a condition for the husband to seek permission from anyone as long as he is an adult and mature. However, if marrying a second wife without the first wife's consent leads to a legal violation or harm, then it is preferable to avoid it.