Yes. If you are a member of the 1995 Section with an existing Added Years or Additional Pension contract, when you are automatically moved to the 2015 Scheme, your Added Years or Additional Pension contract will continue.

You will be given an opportunity to claim the Added Years or Additional Pension part of your pension from the age specified in the terms of the purchase contract, without actually retiring or taking a 24 hour break. You will be able to continue to build up benefits in the 2015 scheme.
If you choose not to claim the pension benefits from your added years/additional pension at the end age of the contract then they will become payable at the same time as your 1995 Section benefits.

As such, and providing a final salary link is maintained, the pensionable pay figure used to calculate the benefits would be the best of the last 3 years pensionable pay.

Additional Pension benefits are not linked to your pensionable pay at time of retirement. However, the amount purchased will be re-valued linked to the increases in the appropriate index (either RPI or CPI).