Child Safety Cord Cover

I am having a prolem with the 2 babies I care for and the Electrical Outlet. First off please know that any unused outlet have plug guards in them- that is not the problem. The problem is the used outlets- they have been unplugging the cords from the outlet. I was looking at the plug guards that cover the entire outlet with the cords still plugged in but the plug that is the most problematic is a 4 plug outlet and I can't find anything in that size. The plug is also behind a rocking chair so they can easily crawl back there but not as easy for me to get there to stop them. Does anyone know of a devie that could help? I have tried thinking of ways to rearrange my furniture to block the plug completely but can't come up with anything.

And please don't tell me to keep a closer eye on the babies. Anyone with children knows how fast little ones can move and that they can do these things before you can stop them.