How to handle removal of Override Age for Pension Calculations on Benefits and Pensions?

Post 23A release there was a change to in the Benefit and Pension card - moving it to responsive UI. This update removed the field 'Override Pension Age' .
This field allowed someone under 22 to opt in before they reach enrollment age, by overriding the min and max pensionable age.

It's been suggested the solution is to configure separate schemes for under 21's, but given the number of schemes we have due to the size of our business this is not feasible. We also need to comply with pension regulations that states an employee has a statutory right to opt-in prior to reaching auto-enrolment and the age override facility that has been removed did enable this statutory requirement to be met through standard functionality.