If the house takes longer than anticipated to sell, that $10,000 could go to $5000 or $0 quickly. 

Are you going to refinance, or sell the home?

I got my realtor from my father who was big into real estate investing over 30 years ago and did very well until some big life's problems came his way which forced him to sell all his buildings.

Tell them the property needs work, is in disrepair, and it's probably better for everyone if they just settle it now by selling the note.

If, for example, I could get hard money to purchase/repair and pay off in a year, I'm confident I could do so without loss, but only if the payments could accrue in the background, collecting interest, without being paid until the house sells.

You must have purchased the property with the intent of holding for investment.There is no statutory holding period before it qualifies to sell and do a 1031. 

So any attempt to bargain sell to save taxes for the mom will result in a failed exchange if examined.2.

We also had single family home which we ended up selling and purchasing a duplex. 

The selling, buying, renting, hunting, rehabbing, etc. and happy to continue learning about this industry hands-on. 

currently have just over $1m to use and am looking at diversifying between a personal real estate rental property to get that 1% monthly rtp, a commercial developer fund that yields 8% a year and 4% after they sell (roughly 4 years after investing), and a managed fund that is liquid and yields 5.5%.