Your contract paperwork will tell them.For example, say you have a Purchase and Sales Agreement with the seller. 

Signing contracts with no money or intention of purchasing!

And you should treat it as such (separate bank accounts, contracts, insurance, etc.). 

Are you currently under contract on a property?

In the end, a lease is a contract. 

My lawyer (thank god) absolutely insisted that the Bulk sale Act or Bulk Sale Contingency be included in the contract.

If you agree on price and your buyers are approved for financing, your attorney relative should be able to set it all up including the contract if both parties are comfortable with terms. 

The side contracting job brings in additional income but the amount isn’t consistent each month.

It has done so in the past several times.Money, especially fiat money of the type we have today is simply a private contract between the lender (depositor) and the borrower...

A better strategy I have heard from folks is that the builder might buy you out of the contract at something like half of the full amount (difference between your purchase price and the market) to avoid having a new never lived in home on the market at less then their asking price for the same model.