Can't trust anyone

You know how you think u can trust family members? Or parents even! Today I called to change my income tax address so it can go to my house, not my moms. So all that was done and good. I also asked the lady if i could get my income tax return sent to my address too. I have not received my income tax return for 2006 and 2004 i think, and they sent them to my moms house. One was almost 400.00 and another was almost 200.00 I asked my mom many times to send them back to me, and she said she did, so I waited and waited. She made excuses blah blah blah. Well the lady said today that all the checks have been cashed, including 2 of my other GST checks! So my mother and her dumb ass bf probably forged my signature and cashed my checks!! I am setting up an investigation, and if it is her, I might sue her, and she will be charged for fraud. Almost 1000.00 worth, I hate doing it, but I feel I have to!