Wanting to keep current townhouse and transition it into a rental unit and looking for some help with that process...Unsure on the timeline of this occurring but wanted to get prepared as best as possible to pull the trigger if a good house in area I'm looking becomes available to purchase.

This likely would be considered a change in ownership triggering a property tax reassessment and that could amount to big dollars depending on when your mother in law bought the house. 

Everyone always says "if the numbers make sense" but people come up with a million and one reason why to not pull the trigger when the time comes.

Price - reduce the price to your absolute minimum - it would need to be 30% below market to move quickly but this will trigger buyer fear so counteract that by..3.

I would caution anyone from being a serial HELOC user though... theoretically a bank can call that loan whenever, and although that is extremely rare, extremely economic turbulence could be a trigger. 

You could also establish the time period to your liking and have it triggered only below a minimum balance.

Have followed along at a distance for a while and just pulled the trigger on pro today made the decision to move full steam ahead with this side hustle. 

You need people that are going to pull thee trigger.

You may want to add that the owner of the tree is responsible for damage to your property, your tenants' property and liability for injury since you have given notice of the risk and requested action. 

If you can lock those three numbers down and the profit potential looks good for you, then it should be a deal that you pull the trigger on.