They may be willing to give some kind of additional credit at closing to sweeten the deal.If you back out, you may be losing part or all of your earned money deposit.Best of luck to you moving forward!

You can even sweeten the deal for the seller a little bit by getting them to wait a few months for their payments.

Now, there is a way to sweeten this deal.  

I want to ensure that I already have cashflow, but my hope is that it will be a sweetener if the beltline(and the business that comes with it) helps my properties appreciate.

On the other hand, if you have only one investor interested, or worse--none yet, you'll have to sweeten the pot with a higher split to the investor.

On the other hand, if you don't have any capital lined up and you have to recruit investors, you'll have to sweeten the pot or they won't play. 

Then my partner adds in that since we aren't using an agent, perhaps the selling agent would be willing to reduce her commission by 1% to help sweeten the deal for the sellers since she won't be splitting the commission with another agent.

I threw in a couple of add-on values to "sweeten" the deal, I am not sure if its enough, or if I need to adjust the rates/splits.

If you can get him down to a 6% rate, that would sweeten the deal, however, you are still only cashflowing ~$75 per unit per month per your projections.If you already know your numbers since you hold similar units, why not update your proforma to represent your actual numbers.  

If you can sweeten the deal by cleaning out the house that's usually all it takes.