Investment Property with partner.

Here is what you need to do:

You want to form a limited liability company with both you and your brother in law as 50-50 members (i.e. you each own 1/2 of the company).  The mortgage company will require a personal guaratee on the loan (i.e. personally liable if the LLC fails to pay the mortgage).  If you are able to qualify for the loan without needing your brother in law to also sign a guarantee, then the LLC be the borrower and you will be the co-signor/guarantor and your brother in law will not have any record of taking out a loan where it will affect his first time home buyer status.  I would keep your business separate from the LLC so that god forbid the property is not a success, the bank cannot come after your personal business.  I would also put your sole prop business in an LLC so that you limit exposure there too.  I suggest that you have a lawyer help setting up these entities and doing the real estate purchase.  Good luck!