Without going into all the details, Word indexes shapes according to the order in which they're inserted and this is what controls your 'tab order'. This order can be manipulated by vba (and the macro wouldn't have to be in the target document).

A simpler solution would have been to overlay the the graphic with a floating table, whose cells are sized such that the formfields end up where you want them. The formfield order would then progress logically from left to right, moving to the next table row as you tab out of each formfield.

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]