Custom furniture for LEED project

I haven't found any other discussions about this - apologies if I missed it somewhere: my client is a custom furniture manufacturer and they are bidding on a LEED CI project. Since all of their products are custom-designed for each client, they do not have a line of "off-the-shelf" products that have already been certified under Greenguard or BIFMA. For this particular project, there will be dozens of workstations and private offices with freestanding office furniture, all manufactured to the same specifications. I'm not sure if I should advise them to seek Greenguard certification or to have a finished sample of each product tested by an independent lab under BIFMA M7.1 and X7.1. Each time that I've worked with furniture in a LEED project, it's been products that are already Greenguard certified. I'd appreciate hearing from anyone who has worked with custom furniture. Thank you!