I've seen some conflicting information saying I should retire all assets and convert the house for personal use and back again to start a new cost basis at 100%
It's not conflicting. That's only "a part of" the process which I won't get into here.
You are perfectly fine to add the remaining percentage as another asset. Note that depreciation is based on the *LESSER* of what you paid for the property originally, or it's FMV at the time of conversion. Most likely, what you paid for the property originally is the lesser amount that will be used for depreciation. I seriously doubt that the FMV today, is less than what you originally paid for the property.
So note that the cost basis for depreciation will be what you paid for the property originally (percentage-wise), plus the cost of any property improvements you paid for since you originally purchased the property in 2012. Don't forget to allocate a portion of your cost basis to the land.
When done, the structure cost basis for all assets, plus the last cost basis of all should equal what you paid for the property originally, plus the cost of any property improvements you paid for since you originally purchased the property.
Note that for each asset that depreciation starts on the date that asset was placed in service. So your depreciation start dates for each listed asset that is a percentage of the total will all be different. However, they're all depreciated over 27.5 years with year one being the date "that" specific asset/percentage was placed in service.
