Ours get under the covers too! I thought they were just spoilt, but it must be yet another beagle trait. We also have one who ends up asleep on the pillow between us. My husband wakes up in the morning with her looking him in the face!
WOW - I just re read everyone's posts, they sound very familiar! Trying to move a comfy beagle is not very welcome at our house. We often get groaned at!