(((hugs))) - I only have two, but my advice is : childproof, childproof, childproof!!! Put gates up (I recommend The First Years Simple & Secure gate:
http://www.thefirstyears.com/search/...?search1=Gates), it's easy to use, swings shut and locks by itself, and is very sturdy) .
And create at least one room (we have 4 - our room, their room, the living room, and now their playroom) that is fully childproofed so you have a safe place to leave them if you have to walk out for a minute or two. And a playyard so if you have to walk out and leave them in there you can put at least one in a safe place away from the other two
.