Why do you not want to update your BirchPress Scheduler Persona so it complains wtith EU Law GDPR, with the new WordPress update 4.9.6 it would not be a problem for you.
Why should all BirchPress Scheduler Persona users in EU buy your business+ to add 1 field to the bookingform, you can also do in BirchPress Scheduler Persona and make a update for your customors that would be good service from you.
I hope that you will rethink your decision not to make BirchPress Scheduler Persona GDPR compatible and make an update for it befor 25.May.
I’m very dissapointet that a client buy a plugin from you and you will not support it when its important, but okey if my cliet got a fine bec of missing GDPR then you pay it, okey !