Trouble with Manually parenting bones to meshes

Hello, I am brand new to blender ( only have been using it for two days now) so far I have Imported a character I made in Sculptris and made it bones and have set up IK and used the automatic weights function to get the mesh to move with the bones, however, my characters face does not move with the bones, the head does, but the face just stretches away from the rest of the model when moved, I think it may be because when sculpting the model the face and head weren’t connected very well, but I liked how the face looked so I stuck with it. now that it doesn’t work I think I have to find a way to manually select the mesh and make it a child of the bone, but every solution I find is simply telling to use the automatic weights function. is there a way to manually select parts of a mesh and make it a child of a bone?

Automatic weights is a shortcut way to set your model and rig up for “Weight Painting

(You aren’t really making the mesh a “child” of the bone, which might be why you keep being misled in your searches. Weight Painting is the Blender term for what you want to do.)