WHAT a farce trying to make sense of these rules , my understanding your lamb is in England so is likely to have a non-eid slaughter tag , you want to UPGRADE it to double tags . The slaughter tag will only have a flock number of its birth ,no individual number ( if it is eid then you will need to read the individual number with a eid reader ) OK SO FAR . You then need to buy and put in a new double tag with your flock number , RED in colour ( because it is a bought in lamb ) . NOW for the bad bit , you have to record all this in your HOLDING REGISTER , the rules state that you must record its full history , hopefully you bought it from the birth holding , so in record of replacement identification you fill in ( hope fully the same in England as Scotland ) date of replacement / new tag flock and individual number / previous tag number / reason -upgrade . I hope this helps