Changing the styles in an Annotation layer

I have a workflow, using FME, that outputs an annotation layer in a file geodatabase.

At first I create some pre-defined Annotation Classes in an empty geodatabase that will be used to style Water and Road text features etc. I note down the AnnotationClassID of each class.

I then run the workflow which assigns the AnnotationClassID noted earlier to each feature based on a feature class attribute from the source data. This workflow also sets the FontSize, Rotation and Vertical and Horizontal Alignments of the Annotation feature.

This runs fine and I can see the results in ArcMap as expected. However, I was wondering if it is possible to tweak the styles of this output Annotation layer?

When I try editing one feature and changing its AnnotationClassID, called "SymbolID" in the attribute table, from a Water to a Road text style of the pre-defined Annotation Classes, the FontSize automatically reduces from a large number, 93543 (set from the workflow above), to 8, drastically reducing it appearance on the map to almost a dot.

I guess this happens because I left the FontSize in the defined Annotation Class as the default "8" in the first place.

What I want to know is if it is possible to preserve the FontSize when changing its AnnotationClassID?