[Pharo-project] ConfigurationOf

Hi, I build the ConfigurationOf for my current project and it works fine, but I have some doubts. My project has dependencies on two other projects, namely Spy and Fuel. In my ConfigurationOf I'm loading these two projects before fetching my code. The point is that, for example, I'm loading Fuel even if it is already loaded in the current image and the same for Spy. Could you help me in creating a ConfigurationOf which only loads those projects if not already in the image and eventually only updates them to the last version? Thanks in advance, R P.s. Here (http://ws.stfx.eu/QOMGC86FZTG) is my current baseline for the ConfigurationOf.