With the Euroshowers Multi Seat there's no need for a separate toilet seat when it comes to potty training your child.  This seat is equipped with a training seat that can be lifted to use the adult seat underneath.  Once everyone is using the adult seat, the inner training seat can be easily removed leaving a regular soft closing toilet seat.

https://www.replacementtoiletseats.co.uk/ourshop/prod_756191-Euroshowers-Multi-Seat-Potty-Training-Toilet-Seat.html