Renewal
I believe next year sometime the CAA are looking at changing the rules on the D-CAT because at present you DO NOT need a renewal which is awesome for me as if my current instructor rating lapses I can still do CPL training, just no PPL stuff. If you are employed by an airline you can do BFR's WITHIN the company on the D-CAT. If you already hold an instructor rating with say a night endorsement or even multi training abilities, then yes you can automatically train night or multi etc on the D-CAT. Any ASL examiner can sign it off however some of them I've been talking to think its a load of rubbish and dont sign them. I got mine from Dave Woodington. I also believe you can just send your log book in to the CAA with $25 if you already hold an instructor rating that is current, and then they just sign it off.