Departed from insane relative that is trying to set me up, how to secure evidence with lawyer in general?

In past I had problems with weed, now my own relatives trying to use it against me. At multiple occasions I found weed flower in the house I used to live untill recently. Im convinced if the police would raided, relative would tell it was mine. I have video of that relative admitting its hers and not ,mine, it happened for the third time, before they tried to scam me from funds that I was eligible for. Im not sure what to do, but I would like that evidence somewhere safe. just in case