Audio issues with movie maker

I have created a project which has now grown too complex to work on movie maker. It now crashes when I try to add something new to the project. I have read that the best way to solve this is to split the project and merge when completed. I do not want to loose what I have done, after spending many hours on it, but I am having real issues due to having multiple audio tracks split and timed to the footage! The slightest edit and the audio is disaligned. I have made duplicates, but to complete 'part two of two' I need to remove the earlier footage/audio. However as soon as I remove the footage (it won't let me select the audio at the same time) it makes the audio move for the rest of the footage. Any way around this?!