Is the marriage invalid if the guardian who conducted the marriage was not the wife's true guardian, but merely an officiant agreed upon by the spouses without the approval of her eldest brother?

For a marriage to be valid, it must be contracted by the woman's guardian (wali) or his agent, in the presence of two Muslim witnesses, based on the Prophet's (peace be upon him) saying: "There is no marriage except with a guardian," and his saying: "There is no marriage except with a guardian and two just witnesses." The guardian, in order of precedence, is: the father, then the paternal grandfather, then the son, then the full brother, then the half-brother (from the father's side), then their sons, then the paternal uncles and their sons, then the paternal uncles of the father, then the ruler (Sultan). The marriage officiant (ma'dhun) does not act as a guardian unless authorized by proxy or if the woman has no guardian. In cases where the guardians refuse to marry her to a suitable suitor, the Sharia judge performs the marriage. This is the view of the majority of jurists, while Abu Hanifa permitted marriage without a guardian. If the Sharia courts in a country that follows Abu Hanifa's school of thought rule this marriage to be valid, the contract is not invalidated. Therefore, if the marriage officiant issues an official marriage contract, it is not invalidated and is considered valid. However, it is advisable to re-contract the marriage to avoid disagreement and as a precaution for one's religion and honor.