Thanks for the above. I've worked out a way using the dataset I hold. The issue that I'm having now is that there are line breaks say if Address Line 4 is missing. It's not always the one address line missing. It could be Line 3 on one letter and then line 2 the next.

See below for what I am using at present which does what I need it to do.

{ IF { MERGEFIELD "Use_Billing_Address"
\*charformat}="No""{ MERGEFIELD "Site_Name"
\*charformat}
{ MERGEFIELD "Site_Add_1" \*charformat}
{ MERGEFIELD "Site_Add_2" \*charformat}
{ MERGEFIELD "Site_Add_3" \*charformat}
{ MERGEFIELD "Site_Add_4" \*charformat}
{ MERGEFIELD "Site_Add_Post_Code" \*charformat}" "{MERGEFIELD
"Billing_Address_Contract_Name" \*charformat}
{ MERGEFIELD "Billing_Address_Line_1" \*charformat}
{ MERGEFIELD "Billing_Address_Line_2" \*charformat}
{ MERGEFIELD "Billing_Address_Line_3" \*charformat}
{ MERGEFIELD "Billing_Address_Line_4" \*charformat}
{ MERGEFIELD "Billing_Address_Postcode" \*charformat}"}