How can I dynamically write each feature class to a separate layer with a modified name when using a single merged feature type reader?

I have a set of feature classes inside a File Geodatabase, which I read using the "Single Merged Feature Type" option in FME. After reading, I perform some analysis on the data.

At the end of my workflow, I want to write the results to a new File Geodatabase. I'm using a Dynamic Esri Geodatabase Writer because I want to write each input feature class as a separate output feature class, keeping the original names — but with a _buffer suffix added to each.

🔹 Goal: If the original feature class was Rivers, I want the output to be Rivers_buffer.

🔹 What I've Tried: I used an AttributeManager to set:

fme_feature_type = @Value(fme_feature_type)_buffer

I also tried setting:

fme_schema_feature_type = @Value(fme_feature_type) (before overwriting it)

But I keep getting this error:

Esri Geodatabase Writer: Feature Type Definition 'Rivers_buffer' was requested, but not defined.

🔹 Additional Info: The writer is fully dynamic.

I believe the error is because I'm using "Single Merged Feature Type", so the original fme_feature_type value is not preserved per feature.

I need to figure out how to track the original feature class names and use them dynamically at the writer with the _buffer suffix.