querry

The marriage is not valid in law and those who abeted is also punishable for the offence.

After completing 21 years, a remarriage before Registrar can be made to legalize relationship.

For present marriage is not legally proper.

Only if some one complaints and provides such proof of DOB then Police may step in.

Even then, a smart advocate can argue that there is a mistake in mentioning DOB by parents.

At present need no worry, and legitimate the marriage after consulting friends and relatives.

As per the extant provisions, boy should be 21 and girl should be 18 years of age so that the marriage shall not come under child marriage.  However, if the marriage is already performed, the marriage is valid. Only those abetted for the marriage can be booked, while the marriage remains valid.

You have not posted the complete facts and the real issue.