I work for SkyDemon and I can generally recommend against adding extra addresses. In the case of France, they ask (in ENR 1.11) for flightplans to be addressed to one central address, where their operatives then forward it on to whomever they deem appropriate. They can get annoyed when addresses are entered manually, since it subverts their official process.
Most of the time, SkyDemon is going to address flightplans exactly as per the instruction given in the national AIP, and the only time you are going to need to add extra addresses is when you know for sure that your plan wont be transmitted to an address that needs it - which is going to be pretty rare.