Basically, you had a not for profit rental. Out of around 36 months, you had a tenant for 5 and a relative for the entire rest of the time a less than full rental value. The way it should have been done is below. I don't know what each return looks like but I'm pretty sure you will need to amend. Since you do not carry on your business or investment activity to make a profit, you cannot use a loss from the activity to offset other income. You do not therefore, need to depreciate.
Not Rented for Profit
If you do not rent your property to make a profit, you can deduct your rental expenses only up to the amount of your rental income. You cannot deduct a loss or carry forward to the next year any rental expenses that are more than your rental income for the year.
Where to report. Report your not-for-profit rental income AS OTHER INCOME Schedule 1 (Form 1040), line 8 (after 2017 TCJA)
If you are filing Form 1040 and you itemize your deductions, you can include your mortgage interest and any qualified mortgage insurance premiums (if you use the property as your main home or second home), real estate taxes, and casualty losses on the appropriate lines of Schedule A (Form 1040).
Claim your other rental expenses, subject to the rules explained in chapter 1 of Pub. 535, as miscellaneous itemized deductions on Schedule A (Form 1040), line 23.[ You can deduct these expenses only if they, together with certain other miscellaneous itemized deductions, total more than 2% of your adjusted gross income. PRE TCJA RULE- NOT VALID AFTER 2017]
Presumption of profit. If your rental income is more than your rental expenses for at least 3 years out of a period of 5 consecutive years, you are presumed to be renting your property to make a profit.
More information. For more information about the rules for an activity not engaged in for profit, see Not-for-Profit Activities in chapter 1 of Pub. 535.
https://www.irs.gov/pub/irs-pdf/p535.pdf
