ConveyProControl treats a sale and purchase as separate matters, each with a unique matter number.
There is not a joint sale and purchase step track - that would be messy, very long, and would often have large sections that would be ignored and if the sale fell through then your left with half the process started and its all a mess.
However we understand the value of being able to know quickly what the other side of the transaction is doing. So we have a JOIN button that connects a Sale to a Purchase.
You can then easily ping pong between the two. We do not cater for a joint sale and purchase completion statement - you do two statements so that its clear to the client which is which and then in your final drafting you would show whether you owe them money or they owe you.