You can achieve that by nesting the fields. For example:
{IF{MERGEFIELD pvgdisclosure}= "PVG Children" "• PVG: You successfully gain and maintain membership of the Protecting Vulnerable Groups scheme in relation to children" {IF{MERGEFIELD pvgdisclosure}= "PVG Adults" "• PVG: You successfully gain and maintain membership of the Protecting Vulnerable Groups scheme in relation to Adults" {IF{MERGEFIELD pvgdisclosure}= "PVG Both" "• PVG: You successfully gain and maintain membership of the Protecting Vulnerable Groups scheme in relation to Adults and Children" "• There are no applicable conditions to this offer."}}}

It's not apparent, though, how your last two mergefields relate to this.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]