Is it permissible, Islamically, to change statements before the judge to invalidate a theft case and release the thieves from prison, based on the request of their families who returned part of the stolen money, and claimed that the thieves have families and young children?

It is not permissible to change statements before the judge, as it involves lying and bearing false witness, which are among the gravest sins. Pardoning offenders occurs before their case is brought before the ruler. As for the issue of wives and children and the loss of future prospects, this is a consequence of the criminals' own offenses, and punishing them serves the public interest by deterring others like them.