First off, as others have said, congratulations. Great kids don't just drop from the sky; clearly, you're doing something right as a parent! Keep up the good work.
Re: investing, you might consider investing the money in your name, but keeping it separate from your investments. If you put it in a custodial account, it could affect her financial aid eligibility when she goes to college in ~12 years, since it will be counted as one of her assets vs. one of yours. (A child's assets are weighed heavier than a parent's in figuring aid eligibility.)