Multi-disc games will ask you to save your game file. Then when you start the next disc, it will load the previously saved game file (or provide options to do so). The only example I can think of would be games like Singstar, where you can swap out discs to load different songs while the game is still running. Dynasty Warriors has something similar wherein you can load data from a different disc (game, e.g.previous game in a series), and then you re-insert the actual game disc back after the data is done loading (prompts on the screen during the process, of course).
I don't know if the game you are referencing has that feature, but the answer is that OPL does not have disc swapping features. However, those scenarios listed above are not multi-disc games, but multiple games within a series making use of data from different games within the series. Generally the former will just ask you to save your game, then you start the next disc and load your save data; the latter requires actual disc swapping which OPL does not provide at the moment.
The solution for multi-disc games is to simply specify that all the other discs (because they will have different disc IDs) use the same VMC file (unless you use an actual physical card).
