Hi.
It depends. Are you just trying to change the name "Chair" for the name of the specific manufacturer name (sorry, had to ask) or are you talking about actually changing the code of the chair?
Changing the text just won't work.
Changing the code on the other hand should... but these types of objects are constructed using macro CALLs, and sometimes the call for a specific object is not in the first hierarchy level (a called macro from inside a macro). You would need to find out where is the code for the chair and substitute that.
Remember to read this:
GS Policy on modifying standard library objects
Best regards.