Grouping for purposes of being a Real Estate Professional is done by including a detailed statement with the tax return.  You would attach a PDF of that statement to the tax return (or mail it with the mailed tax return).  If you are grouping with the business, I think you are looking for Revenue Procedure 2010-13:

https://www.irs.gov/pub/irs-drop/rp-10-13.pdf

If that is not what you are trying to do, please give as more details about what you are trying to do and why.