Help! My sister married a bum! They’re mooching off of my parents! What can I do?

Help!! My sister married a bum! How can I help? He started off good. Military man and good provider for his family. He got kicked out of the military.  When he got kicked out of the military, he, my sister, and their two children moved in with my parents.  Neither one has had a job in the 2-years they have been living with my parents.  Yet, they’re still making babies. Now, it’s 3 children and them living with my parents: I have zero respect for dude! I want to say something but not sure what to say? What can I do?