I am a new member and just wanted to say hello. If you can find a liquid nutrition drink that has good ingredients, perhaps it's not a bad idea but ensure and similar drinks have terrible ingredients. You may want to try juicing and making smoothies but many people have trouble with too many raw ingredients during a flare. I haven't noticed it being a problem for me but my flare diet consists of about one meal a day.
If this is something that is going to be a long term issue I would recommend looking into a heavy duty blender if you don't already have one. We have a bledntec and I LOVE it. EASY cleanup, and a REALLY durable machine. It will make dust of slivered almonds (it skips right over the "chopped" phase, LOL), and I make humus in it frequently with little trouble.
I would suggest making sure you watch the intake of sugar, as the ice cream and things like that will boost it up, which will throw the insulin off. You can also add fish oil, either to the drink or as a pill. You may also want to experiment with butter in it. Raw butter would be best, of course, but if you can't get that, then regular butter is good. I like to drink "bulletproof coffee" in the mornings sometimes, which has butter added in, and one cup can keep me going all morning. It isn't the caffeine because I usually drink decaf, it is the fat in the butter that keeps me moving.
Anything high fat will work, really.
And I agree, green smoothies are strange. I tell all my coworkers that the real trick is that you can't taste the color!!