The seller must trade equal or up in value, invest all equity from the sale and replace the debt, follow specific deadlines, enlist the help of a Qualified Intermediary to provide advice, prepare 1031 Exchange documents, and also hold the funds from the sale.

That Qi (qualified intermediary) should handle all that for you and be your guide.  

The buyer should be using a Qualified Intermediary to handle his 1031 exchange, and the QI usually has the necessary paperwork.

Taxpayers will be required to complete a certification under penalty of perjury to the buyer or REEP (Real Estate Escrow Person, including but not limited to attorney, escrow officer or qualified intermediary) to elect this withholding method.

I am surprised your 1031 intermediary didn't say anything to you while you were making the purchases.

If there’s $220k mort left on the house then I’d have approx $280k in cash to work with that would go to the 1031 intermediary.

You start a 1031 exchange (which will defer all tax and depreciation on gain) by selling a property with a qualified intermediary in place to document and manage the 1031 process.From the date of sale as @Christopher Phillips said you have 45 more days to identify potential replacements and after that an additional 135 days (180 total for those with slow calculators) to complete the process.  

You must also reinvest 100% of your equity (cash proceeds) received by the Qualified Intermediary from the sale of your relinquished property.

You will want to make sure you have a qualified intermediary before you close to hold your funds!

But no, you are not tied to them and don't need to sign anything other than intermediary agreement which just acknowledges you know the broker is representing both sides.