How do I have the head model move around when posing the body model in Blender?

[GameMaster12]

I'm having a lot of trouble trying to get the head to move with the body when I pose the latter model. When I tried the armature deform option (with the head then body model selected in order), it didn't seem to work. This model was ripped from a game called Starlit Season, a game that is made in UE4. Any suggestions on how to have the head model move whenever I pose the body model? Thanks.  The first screenshot is before the pose, and the second is after the pose.