Hey Michael,
However, you may well use one file with different bit changes if you have a g-code routine in the ‘tool-change’ field of the General Configuration Tab of the Onefinity Controller. You might be interested in → this.
There, you will see that at the beginning of the ‘tool-change’ g-code example, all settings of the machine at this point are saved by the command M70 (Save Modal State), and after the manual tool change, the machine will resume the program after the command M72 (Restore Modal State) which tells the machine where it was before the tool change. The purpose of the g-code routine example shown, which you can use in your ‘tool-change’ field, is to allow you to change the tool by driving the router to a defined position, raising the Z, pausing and prompting you to manually change the bit, then after your “OK” click, probing Z in order for the machine to know about the length of the new tool, and finally resuming your running program. You may adust the settings e.g. for the height of your touch probe and also the value with which Z is raised at tool-change position in order to fit your bit lengths. You may also alter the position where the tool change has to be done (if you don’t like it to be done at the home position). Hope this helps, the g-code commands are all explained if you follow the link above. You could also first test them one by one in the MDI field (maybe without a bit first) in order to learn to know them and what they are doing.