Broadlands,
CAP804, Section 4, Part P, p44 deals with conversion of tow ratings. It clearly states that tow qualifications gained before 8 April '18 can added to existing EASA licences. Read the next bit, starting on p46 for adding a tow instructor rating.
The legal requirement to hold an EASA tow rating to tow gliders was deferred until April 2018. You can use your EASA (A) licence to tow gliders & to teach other pilots to tow, even if you don't yet hold an EASA tow rating.
Kestrel539,
Why, oh why, would anyone faff around & spend money getting a whole new licence to do something their current licence already allows them to do?