If you are feeding a new package, put a queen excluder on top of the hive and
put the bags on the excluder.  That way you can lift the excluder to move the
bags without spillage. Next put on the small super and then the inner cover.
You probably also read that the system takes a bit of getting used to to keep
from making a mess.  Once I got it down pat, I've not had any more problems.
Just don't overfill the bags and make sure you get the zip-lock closed good.
Also you might want to start off with quart bags with new packages and nucs.
 
Yes they will go into the bag to get the last remaining syrup if the bags
wrinkles as they take it. I have opened several hives and found the larger
colonies licking a dry bag form the inside.
 
Frank Humphrey