I’ve no desire for harm them to come to harm to your relatives, just aware that this could be the outcome, and was trying to find what the alternatives by googling consequences. It is a crime to steal money, and if found out giving back the money, they could have to suffer the consequences, that’s why I suggested going to a priest.
If they could give the money back secretly, how possible is that be without an electronic trail that might lead back to them, unless they made to restitution in cash. Perhaps you would be best to seek information from a priest and/or lawyer if the relative is nervous about doing so.
Perhaps a discussion in an internet forum isn’t the best place for answers as the internet is electronically traceable. We are warned not to post anything we don’t want ‘out there’ for others to access. It isn’t really right for me or anyone to be involved in something that covers up fraud by suggesting hiding that it took place, so this doesn’t really seem the safest place to ask, but it is possible best to have private discussion with a trusted lawyer and or a priest. That is possibly the best way to protect you relative’s safety and privacy.