Is a marriage considered invalid if a man borrows money from his then fiancée to pay her the dowry? Please note that the husband paid the debt sometime after the marriage. Is recording the value of the dowry in the marriage contract (which the groom had borrowed from his fiancée without her guardian's knowledge) considered deceit and thereby invalidate the marriage contract? And if so, how can the contract be rectified? The bride's guardian claims that the marriage contract has been invalidated and stipulates a divorce to rectify it.

 The dowry, whether it is paid at the time of the marriage or deferred, is valid and borrowing the value of the dowry does not invalidate the marriage. It makes no difference whether the debtor is the groom or any other and this has no effect on the validity of the marriage at any time. Recording the dowry (which is a debt upon the groom) in the marriage contract does not involve deceit in any manner. It is not right to claim that the contract is invalid — if this were the case then all the marriages involving deferred dowries would be considered invalid.
The ruling
The condition set by the bride's guardian to rectify the contract is inconsequential because the contract is valid.
And God Almighty knows best.