This is when you're in control of Lily.
In the house, you will be tasked with making breakfast for yourself.
1: Get Dougal to interact with the string on the cupboard door, then with yourself to get the bowl.
2: Now, get Dougal to interact with the door. This will distract him. Then quickly interact with the bag of oats hanging from the wooden beam in the top right of the screen. If you do this quickly enough, you will be able to climb the unit without Dougal pulling you back down.
The achievement will unlock shortly after.