So add all pages as a single PDF, i.e. fronts and back with their variable frame layouts and specified field names within. Then name each page(Fusionpro>>Manage Pages>>Page Usage
Set the pages to “Unused”. Instead of naming the pages, giving them unique names for the fronts
Then create the rule, (Create Rules>>New>>>Callback>>OnRecordStart). We will use the field values as in this sample code.
The rule below can be simplified greatly by only activating the page you need, since all the pages are marked unused initially.
So it can be reduced like this example:
if (Field("Design") == "Basic")
FusionPro.Composition.SetBodyPageUsage("Basic Page 1", true);
if (Field("Design") == "Featured")
FusionPro.Composition.SetBodyPageUsage("Featured Page 2", true);