While in a transaction, you can add or delete assets from that transaction while still in the negotiations phase of the transaction.
Adding Assets to a Transaction
To add assets to a transaction, click on the Assets tab and then click the text labeled
"+ Add Assets to Transaction." This will open a drawer for you to add other assets owned by that seller.
Select the assets to add and click the "Add to Transaction" button.
You will now see these assets in the dropdown above the Note Details.
Deleting Assets from a Transaction
To delete assets from a transaction, click the Assets tab and then click the text labeled "x Remove Assets From Transaction".