Ok this one’s kinda long and funky. I will attempt to make a video or add photos at a later date but I figured I’d write it out while I remember how to do it.
So, have you have wanted to separate parts of your model without losing multi-resolution or changing the topology at all? Have I got the trick for you!
Step 1: create a mask or polygroup of the object you’d like to split apart
(I would recommend a polygroup just in case you need it later)
Step 2: Create a clone of the object to save the original, then use the trim tool (with ‘none’ selected as the closing action) and trim out everything you want split apart
(You will probably want to be on your highest subdivision level in multi resolution, although this may cause some issues I will address at the end)
Step 3: Invert you mask on the untrimmed clone and repeat to get the other part
(This is the last step if you don’t care about multi resolution)
Step 4: Using the multi resolution tab, click ‘rebuild lower level’ to regain your multi resolution layers, and you’re done.
Note: If ‘rebuild lower level’ does not work you’ll have to go to the highest level that it does work for, and then subdivide your model again and use reprojection (under the misc tab) to regain your high res details. There should be guides about doing that but I can make that too if necessary.