I sold my half share of a owner-occupied duplex last year to other co-owner via quit claim. I am reporting the sale & have questions re: business % use changes, quit claim/settlement, and my sales price vs original basis.

For all time of ownership (2008 - 2023) one unit was primary residence/home (35%) and the other unit was a rental (65%). In 2008 I set up cost basis w/ 65% business usage and TT properly populated the building depreciation for the rental portion). I've always entered expenses/income under the 65/35 split or 100% if all rental.

FIRST ISSUE - Business % use and depreciation. This year I noticed the rental property had 80% business use listed instead of 65%. I reviewed previous returns and I've been mistakenly reporting 80% vs 65% since 2015(!). The total depreciation deduction I've taken from 2008 - 2022 does match what TT shows for prior depreciation. I have changed to 65% for this year (2023) and I will report the sale as a split 65/35 for rental/home. All depreciation taken in those years will be recaptured. Will it be a problem with the IRS that the average of the bus use reported over time doesn't match the 65/35 split I report for the sale, or that I changed that back to the correct/original 65% this year? Do they even care if I'm recapturing? Is there anything else this affects? I would prefer not to have to go back and amend previous years or hire someone to file a 3115, if at all possible. Looking for the easiest legal way to be done with it.

2nd ISSUE - Quit Claim & Legal Expenses. I filed an action to partition in 2020 and we ended up settling outside of court in 2023. He paid, I quit claimed to him, case was dismissed. No mortgage so no bank settlement sheet, all I have is the PTTR which reflects sales price accurately. First, does a quit claim affect anything at all regarding how I report the sale (or anything else I should be aware of)? Secondly, can I claim 65% of my legal fees as closing costs? Legal services were necessary to recover my investment/equity, produce taxable income, deal with management of the rental property and co-owner's harassment of the rental tenants. I consider fees I paid from 2020 - 2022 are gone/lost; I am only referring to fees paid in 2023. I originally deducted these fees under rental expenses but read that was no longer allowed so included them in closing costs.

3rd ISSUE - Sales Price vs Cost Basis I'm confused about how to report my sale after reading this discussion with @AmeliesUncle (https://ttlc.intuit.com/community/tax-credits-deductions/discussion/tax-year-prior-to-2020-rental-pr...). In 2008 my purchase price (116750) was half of a 233,500 city assessment, which I used to set up depreciation basis but FMV was 258,500. That was the correct way to set that up. But when reporting my sale, am I allowed to use something other than original cost basis I set up for depreciation purposes? Am I able to use 2008's FMV as my basis which would result in less gains? Is that accurate and legal? If so, I assume the only way to do that would be to close out assets as personal property then report manually in Sale of Business property, correct? Which maybe I need to do anyway because of accidental varied business use?  I'm very confused why/when you would use original purchase price vs. FMV in determining cost basis for reporting the sale. I want to pay what I owe but don't want to raise flags or questions. Ready to be done with this chapter of my life and I don't need a problem with the IRS.

Thanks for helping me!