If both of you have ownership interest, then you need to form a separate LLC.

I try to buy on ACTUAL numbers, not a pro forma that illustrates projected operations.  

.$2,135.00MONTHLY INCOME$1,694.08MONTHLY EXPENSES$440.92MONTHLY CASHFLOW14.08%PRO FORMA CAP$9,853.40NOI$22,125.00TOTAL CASH NEEDED23.91%CASH ON CASH ROI13.59%PURCHASE CAP RATEExpensesIncome50% RuleTotal operating expenses:Mortgage expenses:Vacancy:$170.80Repairs:$213.50CapEx:$106.75Electricity:$50.00Water & Sewer:$162.00Insurance:$120.00Management:$213.50P&I:$380.20Property Taxes:$277.33$72,500PURCHASE PRICEPurchase Closing Costs$2,000.00Estimated Repairs$2,000.00Total Project Cost$76,500.00After Repair Value$70,000.00 Down Payment$18,125.00Loan Amount$54,375.00Loan Points$0.00Amortized Over30 yearsLoan Interest Rate7.500%Monthly P&I$380.20Total Cash Needed$22,125.00 Financial Info2.79%2% RULE $15,625.00TOTAL INITIAL EQUITY2.83GROSS RENT MULTIPLIER 2.16DEBT COVERAGE RATIOAnalysis Over Time3% /yearEXPENSE INCREASE 3% /yearINCOME INCREASE 2% /yearPROPERTY VALUE INCREASEYear 1Year 2Year 5Year 10Year 15Year 20Year 30Total Annual Income$25,620.00$26,388.60$28,835.54$33,428.29$38,752.55$44,924.83$60,375.21Total Annual ExpensesOperating ExpensesMortgage Payment$20,328.97$15,766.60$4,562.37$20,801.97$16,239.60$4,562.37$22,307.82$17,745.45$4,562.37$25,134.21$20,571.84$4,562.37$28,410.77$23,848.40$4,562.37$32,209.20$27,646.83$4,562.37$41,717.40$37,155.03$4,562.37Total Annual Cashflow$5,291.03$5,586.63$6,527.71$8,294.08$10,341.78$12,715.62$18,657.81Cash on Cash ROI23.91%25.25%29.50%37.49%46.74%57.47%84.33%Property Value$71,400.00$72,828.00$77,285.66$85,329.61$94,210.78$104,016.32$126,795.31Equity$17,526.25$19,494.41$25,837.43$38,134.84$53,197.53$71,986.64$126,795.31Loan Balance$53,873.75$53,333.59$51,448.23$47,194.77$41,013.25$32,029.67$0.00Total Profit if Sold *-$1,449.73$6,062.22$30,895.02$80,784.39$143,073.13$220,258.21$432,774.81Annualized Total Return-6.55%12.87%19.10%16.62%14.34%12.71%10.60%

It takes a HUGE chunk out of my cashflow, and is often not predicted accurately in pro formas, so do your own due diligence to predict cashflow. 

Would you include a Pro Forma Prop Mgmt expense in your calculations?

.$215,000 Purchase Price$3,800.00 Projected Monthly Income (with all 8 units rented)(Current rent is actually $2,850 with 6 units rented)$2,177.50 Monthly Expenses$1,622.50 Monthly Cashflow13.92% Pro Forma Cap$29,928.00 NOI13.92% Purchase Cap RateTotal operating expenses: $1,306.00Mortgage expenses: $871.50 Vacancy @ 7%: $266.00 Repairs @ 5%: $190.00CapEx @ 5%: $190.00Insurance Est.: $60.00Management @ 10%: $380.00 P&I (30 yr, 4.5% estimate): $871.50Property Taxes: $220.00***Total Monthly Cashflow using 50% Rule: $1028.50

.)$620.33 MONTHLY EXPENSES$379.67 MONTHLY CASHFLOW9.17% PRO FORMA CAP$8,712.00 NOI$20,100.00 TOTAL CASH NEEDED22.67% CASH ON CASH ROI9.90%PURCHASE CAP RATEAccording to the numbers I think it'd be a great investment if I could find a way to get the $20,100 I need.

(Edit:  OK, so form a Joint Venture, which would protect both parties contractually. 

I will however be inheriting 3 multi families (once probate is finished). my wife and me are buying a short sale to live in as a primary residence, well it needs to be approved my the bank 1st. we currently have 1 quote form a mortgage lender with my current state of assets.my questions are 1. 

I will not buy based on seller's pro forma expectations.