Long term residential rental real estate is not a sole proprietorship by any stretch of the imagination. A sole proprioetorship produces non-passive income and gets reported on SCH C as a part of your personal 1040 tax return. Income from rental real estate is non-passive and therefore gets reported on SCH E as a part of your personal 1040 tax return. If you have not been reporting your rental income on SCH E in the past, then you have a major issue that is beyond the scope of this forum, and will require professional help to make things right. This is especially true if your state taxes personal income, as if you reported it incorrectly in the past, then you have a double-whammy.
If you did "in fact" report this on SCH E in the past, then work through the property and each individual asset to indicate you converted the property to personal use, one day before it was acquired by the partnership.
On the 1065 partnership return, the in service date will be exactly the same as it was on the SCH E, since there was no change of ownership that occurred due to a taxable event. (such as selling the property)
Additionally, since the in service date can not be before the partnership was established, that means your "date established" for the partnership must be the same as or before the "in service" date of the property. Since there is no ownership change, things will be fine. (The same people that owned the property, are the same people that own the partnership - so there is no taxable event here.)
