How do you deal with someone who tries to undermine you on the job.?

The company I work under a different boss hired someone with no experience, in a field that requires great experience, the person hired has someone who covers her like someone who wipes her a double s, and I do twice the work they both do and while I do get credit, her and her trainer seem to undermine me at every chance, instead of coming to me, they go whine to the boss, who listens to them because he is new to the company (not the one who hired) and feels he doesn't want to be left in the dark and wants to know everything. I would not have hired the person., but these girls make big mistakes that I go to them about and not over their heads. They absolutely do not follow chain of command as my boss allows them to continue. If I would have chosen to train this person, I would have done it correctly at the expense of slowing down the work. So it seems all I can do is cover my **@@@**. How do you deal with these kind of beasts and maintain sanity??