You really shouldn't need macros for any of this - at most a page of instructions, some of which you'll need anyway. Trying to recreate the mailmerge main document programmatically every time it's needed merely create a maintenance nightmare; much better to have one saved that you only need to open to use.

Your Excel data file can be edited from within Excel, prior to the mailmerge. Or it can be edited at mailmerge time from the mailmerge main document, via Edit Recipient List. Without a great deal of coding, this part can't be done from a macro.

Provided you don't answer 'No' to the SQL prompt, the mailmerge main document (which you'd have saved as a read-only file with its completed table and all the autoshapes in place) will find its data source automatically and, after any necessary record editing/filtering is finished, all the user need to is click on Finish & Merge, then choose the destination.

PS: You refer to a 'master document'. In Word parlance, that's an entirely different thing from a mailmerge main document.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]