Pseudo dynamic memory management in Virtualbox, otherwise know as memory ballooning.
After looking for a way to dynamically allocate memory in Virtualbox, I discovered it’s not technically possible. With that being said, there is a method that Virtualbox calls memory ballooning, due to the way memory is handled, that can serve basically the same purpose. In the documentation, there is a section just for Memory Ballooning. Hope this helps someone.