Two balloons inside another balloon

Inflating two balloons inside another balloon on my pump: I start off inflating a 17-inch balloon, and deflate it a few times. Then I stuff a 12-inch balloon inside it and overinflate it, then it pops inside the 17-inch shortly after I get it tied. Then I stuff another 12-inch balloon inside the 17-inch, inflate it, then tie them both.