If you have trouble drinking them you can always use a nasogastric tube. My son did this when he was doing EN. His was supplemental not exclusive (EEN). He used a prescribed formula (peptamen 1.5). He was given the option of using Ensure or Boost but had trouble with the texture so opted for the NG tube. He would place it every evening, take in the formula while he slept, then he would remove the tube before showering every morning.
There is a subforum about Enteral Nutrition in the treatment section. There are a number of kids who have been on EEN or EN orally and by NG, NJ or various other means.
So glad things seem to be working well for you on EEN.