Just as a reminder, it's not a one-time shot by a mom who was having a bit of mom-worry but had no idea that she was committing a serious criminal act that could easily place her in an orange jumpsuit.
Rather, the family member has laughed at the OP when he's asked them to stop and when he's explained clearly that these are criminal acts. The clear implication is that the family member won't stop and will be doing more of it and thinks it is funny.
That said, I still have not urged the OP to file charges against specific people, but rather asked the OP to consider that option and to consider how he'll feel (and what the fallout will be with other family members) if he gets his mom or brother arrested and even put in prison.
One thing to explore is filing a police report based on the indisputable fact that crimes are being committed. When your house is burgled, you don't have to identify who the robbers are to file the report. A police report is an important step in getting cost free credit bureau freezes and other tools for addressing the ID theft.
