As such existing properties are often grandfathered in with their existing footprint, even if current zoning would require a smaller one due to lot size.

I don't think I could get a very large loan from the bank because I'm currently paying on a mortgage and don't have a lot of passive cash flow.

You have property management, insurance, loans/mortgages from banks and lenders, you and tax person, and maybe someone like me who provides you with already vetted deals from trusted providers.Yu can get some mid-size deals that maybe pay $300/month or less financed deals that pay about $800/month.All this and a lot more details I am happy to discuss with you and your wife is related to your investing business.Independent of that should be where you want to live.

They are very generous and want to help us with the mortgage.

So, I was assuming you have a rehab amount built into your current existing loan that you could draw from OR use your own cash. 

You also haven't left room for property management (if you intend to use it).So long story short, if you're BRRRRing or using a mortgage to obtain the property you are going to be cashflow negative or close to it:$1,150 - $1,000 - $90 - $62.50 - $62.50 - $62.50 = -$127.50My personal criteria is that I won't buy any single family rental unless it cash flows $250/month after all average expenses and provides a minimum of a 20% cash on cash return.

Remind yourself that once you get this thing rented, someone else is helping you pat down the mortgage, keep your living expenses low, you get to reap the rewards of appreciation and the tax benefits too.

When borrower refinance cash-out an old mortgage with a 12 Bank Statements lender while applying for a new mortgage with another 12 Bank Statements lender at the same time, will refinancing the old mortgage affect the DTI, and qualification for the new mortgageBecause the 1003 shows the liabilities and mortgage payment of all mortgages?

The pull back in these markets is due to a confluence of many factors, but it started with these environmental factors:Low interest rates and easy financing for new projects.Structurally high rent growth on existing inventory.High wage growth and high job growth.Very low vacancy.These factors led to floods of institutional capital coming to these markets to snap up existing multifamily inventory and build new supply to meet demand.For these markets, the last 5 years have been a seemingly never ending party!

Current mortgage is 1748.