In the assets/depreciation section, enter the property itself first. Work it through and it'll set things up based on your selections, for the 27.5 year depreciation. When you're done with that entry, leave it alone. You'll see it listed when you return to the assets/depreciation list upon completing the entry. Then click the "Add Another Asset" button and press on with your next asset. Understand that anything you classify per MACRS as "residential rental real estate" will be depreciated over 27.5 years, and SEC179 and SDA is not an option.
Typically, 5 year property are things like appliances, and 15 year property are things like land improvements; such as a retaining wall. Things classified under MACRS as appliances while depreciated over 5 years, should give you the option of selecting accelerated depreciation, such as the SDA. I'm not sure about 15 year assets.
Just be aware that most likely, all this work to separate things out is not going to have any impact on your tax liability anyway, since long term residential rental real estate with a mortgage on it is practically guaranteed to operate at a loss anyway.
