You will find that engineers being what they are interpret the rules as THEY see it, not necceserily how Agusta (service letter) and more importantly EASA now viewinsurance it. The engineers think that because this situation has been ok since time began that its still ok, which I can tell you is incorrect and is why you should now take fresh instructions from the CAA (Mr McMillan East Midlands office) who I am sure will enlighten (frighten) you.
Of course the biggest problem here is that you have to make a claim on your insurance to be told that you have unwittingly invalidated your insurance by having parts fitted which are not certified by Agusta.
My particular machine had brand new Bell tail rotor blades fitted which HAD to be changed to Agusta blades, guess what no part used blades anywere and eventually Agusta had no option but to certify said blades because they are no longer in production. So if the new owner dings a blade in the near future the machine is grounded indefinatly because Bell nor Agusta now manufacture those blades.