Permission Sets

When doing a conversion from a previous version to BC14 (in my case from NAV2017 to BC14) there is an issue with Permission Sets that are not base but custom. The custom Permission sets that are converted are defined as type (scope) = System so that they cannot be modified/updated.
Is there a way through a pre- or post-conversion process that can change the Type/Scope field of the Permission Set into 'User Defined', so that administrators can have access and can make changes?

It looks like the only way to do that is to use the action ‘Copy Permission Set’ on the Permission Sets page (9802). A copy of a Permission Set can be modified since the type is defined as ‘User Defined’. But that means that all Access Control records for Users must be modified as well.

Any suggestions?