Yes
and Yes.
Honestly, I'm not too concerned. The US and soviets have been doing that for 30+ years. It gives China a nuclear bargaining chip, but it's not significantly better than what they previously had. I'm also not too concerned because of the direction defense technology is going: we are focusing a lot of resources on "shooting down" ICBMs before they would lose their payload faring and separate the multiple re-entry vehicles - which easily counters MIRV capabilities.