Is it permissible to marry a chaste Christian woman in a European court in the presence of two Muslim witnesses, one Christian witness, and a female officiant, knowing that it was done without her family's knowledge?

If a woman from the People of the Book is chaste, it is permissible to marry her, provided that the শরী‘আ-compliant conditions are met. Offer and acceptance are essential pillars without which the marriage is not valid. The testimony of two just Muslim men is sufficient for its validity. However, the aforementioned marriage is invalid according to the majority of scholars due to the absence of the woman's guardian (wali). It must be annulled immediately, and one must stay away from the woman until a valid contract is concluded. This is unless a Shar‘i judge rules it to be valid, or if you follow Imam Abu Hanifa, who does not stipulate the presence of a guardian.