Whilst the UK has a fairly pragmatic view of this, other member states do not. As well as the reference that Whopity has provided, there is one other that is relevant:
FCL.205.A PPL(A) Privileges
(b) Notwithstanding the paragraph above, the holder of a PPL(A) with instructor or examiner privileges may receive remuneration for:
(1) the provision of flight instruction for the LAPL(A) or PPL(A);
(2) the conduct of skill tests and proficiency checks for these licences;
(3) the training, testing and checking for the ratings and certificates attached to these licences.
This has been taken by more than one competent authority to mean that the holder of a PPL(A) may not instruct or examine for a rating that is to be attached to any other licence whereas, of course, it refers only to receiving remuneration for such activity.