Hi Nattily! I used to add olive oil to my shake and other things and it was easy to do and was not noticed. However, drinking it straight in any great quantity( a few ounces) might be challenging. Does it work? It seemed to pack a punch for me but I was also slamming a ton of other foods so I can can't say if it is any better than cream.
I think you have to start slow and get accustomed to larger amounts just like building your capacity for more and more food. You'll have to put up with any side effects for a while until you start to see and feel the results of your hard work.
I think those two items are strong tools to get you where you want to go.
Stick with it and it's going to happen for you. Sooner or later ....You WILL be fat!! Go for it!!

In print it sounds like a selfish ultimatum and I hope She knows you well enough that your "request" is well intended. It's really about what she needs not what you want.
Hope it works out.