Steve
I don't think editing the Building Blocks in anticipation of using them in the current doc is a good idea. For starters, the template should be 'document agnostic' because I might have multiple docs open at the same time and if I had hard coded the [n], [e] and [m] fields in the template, it might only be useable in one of those documents until the macro is used to reset them to suit another document.

Investigate linked content controls and then put those into the template building blocks. As an introduction to this, go to Insert > Quick Parts > Document Property and pick a couple of those entries. Now embed those into some random bits of text (such as a couple of your building blocks. Notice how if you place two instances of the same linked CC into a doc, you can edit either one and the other one automatically updates. Now go to a second document and paste that same content into that document, and edit the CC there to see that the same CC can show different values in different docs - because the linked metadata can be different in both.

Including linked CCs in your quick part building blocks allows you to set the value of the document property so that any subsequent content pasted in which includes a CC linked to the same property will automatically show the right info.

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Andrew Lockton
Chrysalis Design, Melbourne Australia