Is the marriage contract considered valid if the guardian is the maternal aunt's husband instead of the deceased paternal uncle, in the event of the father's death, the young age of the brothers, and the existence of disputes with the paternal uncle?

The marriage contract is not valid without the presence of the woman's guardian (wali) or his representative, according to the majority of scholars. If your brothers have not reached puberty, then your paternal uncle has the most right to be your guardian. The marriage is invalid according to the majority if you married without your guardian's permission or authorization, and the existence of problems with your paternal uncle does not negate his right to guardianship. Therefore, the marriage must be renewed in the presence of your rightful guardian now, and if one of your brothers is an adult, he has a greater right to marry you off. Children born before the renewal of the contract are attributed to your husband. This marriage can be enforced if a Sharia judge rules it to be valid, and it is valid according to the Maliki school if your aunt's husband is from your agnates. However, it is safer to renew the contract to avoid disagreement and to act in accordance with the opinion of the majority.