OOP Design Dilemma

I would personally do it something like this:

Global Engine:TEngine

Type TEngine
' when created, sets the Engine variable to this so other entities can easily access it
End Type

Type TEntity
' all the basic entity handling, positioning, etc
End Type

Type TCamera Extends TEntity
' your camera!
End Type

It's all personaly preference and using OOP to the best you can.