A family of Microsoft word processing software products for creating web, email, and print documents.
In general, blank lines are automatically suppressed, but only if they end in a paragraph break, not a line break. Consequently, the default is not a solution for me and perhaps not for you, either. So you have to use an IF field. Assuming your two address lines are the merge fields Address1 and Address2, you'd have something like this.
{ MERGEFIELD Address1 }<line break>
{ IF { MERGEFIELD Address2 } = "" "" "{MERGEFIELD ADDRESS2}<line break>" }
The way that will actually appear in your document is:
{ MERGEFIELD Address1 }
{ IF { MERGEFIELD Address2 } = "" "" "{MERGEFIELD ADDRESS2}
" }
By putting the line break inside the FalseText quotes, you ensure that thereis a line break only if the line contains text; otherwise, there will be no line.