Child Damage Mitigation

Not certain if you are concerned with the speakers toppling, or other damage.

If possible tipping/toppling is the concern then look into after market stands that are more stable then the "stock" stands (Mye stands for an example).

You could also "affix" the stock stands to the floor with a few small drill holes and suitable wood/masonry screws.

Another option would be to place a pair of "target" speakers next to the Maggies and plaster them with My Little Pony stickers.

I would suggest, due to their attention getting looks/think Transformers, a used pair of Wilson Audio Alexandria speakers.

DeKay

We raised five children with various Maggies in the house the whole time. It was labor intensive, but as some others have mentioned, letting them know the speakers, and the rest of the audio equipment (and the stove, and AC outlets, and the stairs, etc..) are not to be touched worked for us. One must use the theory of repetition. I’m not a “man-cave” guy... our nice system has always been in the family living room. Everything survived. Now we have twelve (!) grandkids, and guess what? The “No honey, don’t go near daddy’s/pop pop’s speakers” lessons started all over again! Lol. All the kids have always loved the music, so when they’re old enough to understand, I explain that broken speakers play no music. They get it. Then the older ones teach the younger ones. I love my kids, and grandkids more than my stereo (of course), but I expect them to respect the things that are important to us. And fortunately they do. 

I used 2 of those plastic gates to close off the living room where my system was, also used those for the stairs. Get them put up asap that way the kid is used to them and not inclined to mess with them. Worked on my son, and my dogs. With the dogs after they got to be about a year old I could take down the gates and they just wouldn’t go in the room. 

The famous Bose 901s were either set on a "tulip" stand
or suspended by chains from the ceiling.
I think you can see which method would work best
for your situation.
Enjoy you new gift. 
Stereo gear won't be a priority for next 18 years or so.

In a little different approach, I feel the kids should be allowed to touch all the things with some directions, if possible. However, and that is why bottom-heavy large-base speakers were my recommendation, it may be unavoidable that a child bumps into something while growing up so that particular thing may need to be set up safely.