enhance Render Tool for dynamic output file rename

[fharper]

In Render tool you can use a field to group by and use that field to alter the output file name somewhat similar to the output tool.  Unfortunately it is not exactly like the output tool.  Usually you have a table tool and or layout or visual layout tool before the Render.  In my most recent scenario I have several outputs I use the Table tool for to format, the text tool to generate headings and the visual layout tool to organize these headings and tables into coherent sections on a final output used as a dashboard. 

Fine and dandy except a new requirement now divides these data based on client so I tried to find a way to pass the Client code through to the Render tool so it could dynamically alter the output file so each client gets their version without manually creating multiple replicated streams to format.  But the Render tool requires a field and if I am passing a table it can't reference columns (fields) within the table and if I build a client code field to pass outside the table I can't seem to find a way to tag it to the table  and text going into the layout or in some way pass it into the layout tool in a meaningful way to reach the Render tool for use in dynamic rename of output file.

I wish there was a way to pass a field into the Render tool to modify output file name whether feeding it tables or other data or mixed elements.  Maybe a pass through element or something?