Not using the AddressBlock field would be a start - then use conditional
fields to place the 'return' and the content of fields that may be empty
thus
{ IF{ Mergefield Fieldname} <> "" "
{Mergefield Fieldname} { IF{ Mergefield Fieldname2} <> "" "
{Mergefield Fieldname2} { IF{ Mergefield Fieldname3} <> "" "
{Mergefield Fieldname3}etc

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Graham Mayor - Word MVP
My web site www.gmayor.com
Word MVP web site http://word.mvps.org
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> Between the line with the persons name and the organisation name mail
> merge is inserting a blank line into the address block, its 'hitting'
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>
> Baz