For a marriage to be valid in Islam there are a few things which must be checked first.
Can the to be spouses marry each other? Are they blood relatives? Is there any prohibition for this marriage.
A Muslim man can further marry a Christian or Jewish or what ever is considered as from the people of the book woman or girl as long as she is chaste, that means either she is a virgin or she has been legally married and divorced or widow from a prior legal marriage (legal refers to her religion not a man made law) or if she has committed zina and sincerely repented.
Note that some scholars discuss whether or not this is general permission as for example it seems rather unlikely to be applied for the case of non-Muslims who fight the Muslims. One could also discuss whether or not this is applicable for Christians and Jews nowadays. If this person believes in one God that should be fine. The Qur'an more than 14 centuries ago already referred to people of the book (partly) as believers, disbelievers and mushriks nevertheless one of the last revelation actually is verse (5:5) which I will quote later.
Now as said if the women keeps her religion and is permitted to be married to a Muslim man she needs a wali from among her religion (father, brother etc.) who must be present.
Any woman whose marriage is not arranged by her guardian, her marriage is invalid, her marriage is invalid, her marriage is invalid. If (the man) has had intercourse with her, then the Mahr belongs to her in return for his intimacy with her. And if there is any dispute then the ruler is the guardian of the one who does not have a guardian.” (Sunan ibn Majah)
in the Qur'an this is what is referred to by desiring chastity:
This day [all] good foods have been made lawful, ... And [lawful in marriage are] chaste women from among the believers and chaste women from among those who were given the Scripture before you, when you have given them their due compensation, desiring chastity, not unlawful sexual intercourse or taking [secret] lovers. ... (5:5)
In Islam basically also a wakil (a person who has been authorized by the wali to act on his behalf) is allowed, I'm unclear whether this applies for non-Muslims too, but I honestly don't see a reason why it shouldn't, but I'm not an authority and one must check whether the wakil in such a case can be a Muslim etc. as this might be an issue as a Muslim can't have a non-Muslim guardian and if guardianship is considered as higher than wakala (acting on behalf of someone) it might create confusion whether a Muslim can be wakil or not due to the verse used as evidence to lift guardianship from a non-Muslim if a person has converted which says:
... and never will Allah give the disbelievers over the believers a way [to overcome them]. (4:141)
Note that the hanafi madhhab allows an experienced woman (widow, divorcée) to marry herself, but I have no clue whether this also applies to non-Muslims as later hanafi scholars are hardly allowing marriage to women from among the people of the book (See According to Hanafi jurisprudence, marrying Jews or Christians is Makruh Tahrimi. Why is it Makruh Tahrimi even though it is allowed in the Qu'ran?).
If she converts a non-Muslim can't be her wali this is the only case were an imam or a (Muslim) person of her choice (not you!) may play the role of her guardian for the marriage.
So you have a couple of choices:
- Either her wali is present
- or he authorizes a person (preferably from his own religion) to act on his behalf and be present when the nikah ceremony is done.
- You may also delay everything (including consummation of marriage) until you do the civil ceremony and have at least two Muslim witnesses (of trust) present there. But you can announce that you will marry her at your home place
- And she could convert if she want to (without pressure).
These are at least the options I had in mind.
Finally note that most scholars would advise you to marry a Muslim instead of any non-Muslim girl. As you need to have in mind that this person would educate your children one day etc.
Can we marry non-chaste women of the book al kitaab?