I would like to create a simple escrow account with two preauthorized timebound transactions, but not sure how to approach the problem. I am fairly new to Stellar, so correct me if I am wrong. 

I have to build two transactions with different destinations but same sequence number (one higher than current on the acc). Third transaction will contain 2 signers with `tx1.hash()` and `tx2.hash()` with some weight e.g. 2 on both. This one will be signed and submitted. 

How can I send same preauth transaction in the future so it matches the signer key? Do i have to store the original transactions as XDR? I am using stellar-sdk, building both works, signers are also getting created. Just need to get on the right track, maybe whole approach is completely wrong.