You can enter potentially exempt transfers (PETs) that predate the beginning of the plan on the Carryover Assumptions screen. This screen is used to capture all manner of tax and pension related information that predate the beginning of the plan.
Go to the Carryover Assumptions screen. Scroll down to the Nil Rate Band Carry Forward & Previous PETs section.
Click Previous Potentially Exempt Transfers.
This panel gives you the option to enter PETs made up to seven years before the start of the plan.
Since PETs are tracked for the potential IHT liability of the individual, be sure to select the appropriate person who made the gift on the screen's People selection on the left.
You can see failed PETs in the Legacy tab. For example go to Legacy and run the 'If both die today' scenario which assumes mortality at the end of plan year 1. Click on the dots and dashes to see the details as shown below.