It is not a silly question.
Yes, the pigs should have your ear tag in or slap mark for a forward move from your holding.
There is no need for pigs under a year of age to be tagged for a movement between farms so if people didn't tag weaners this problem would be largely removed. However, weaners through an auction will always be tagged.
It is a rather daft idea that a tag is removable or that on the hardest animal to restrain you would be expected to remove a tag!
When you fill in the eaml2 form you can only enter herd marks and slap marks registered to you. I think I would just add my tag and in the box where it asks if the pig has any other identification I would say yes, previous holding tag and tell them that herd mark too. I would also tell the abattoir and if yours has the same system as ours (white board on pen door) I would write on the door my name, details of pigs and say double tagged.