Returning text from a BR# inside GetDataCell — possible?

I'm building a cube view column that shows combined annotations from descendants. I'm calling an Finance Cell Service BR from inside GetDataCell so I can pass dashboard params needed for the logic. 

GetDataCell(T#|CVTime|:BR#[BRName=..., FunctionName=CombinedComment, Flux_ID = {fluxID}]:U8#{ud8}):Name({ud8} Combined). I need to the UD8 POV member because that distinguishes what type of comment it is (CMvsPM, CQvsPQ, CMvsPYM, Ect...).

The BR returns a String, but GetDataCell expects a numeric amount so the text doesn't render in the cell. Pointing the column at V#Annotation doesn't help either.

Has anyone gotten BR-returned text to display in a GetDataCell with full POV/param context? 

Thanks,

Ben