Thunderbolt to Firewire Target Disk mode?

I have just been to a friends and she has a 'dead' graphics chip on her MBP 15 inch, a few years old.

She has bought a new 13 inch MBP with El Cap and wants to access files on the old MBP

I popped down there today with a Firewire to Firewire cable, hoping to use target disk mode but the new MBP has no Firewire..only this Thunderbolt port.

I have see that there are TB to FW adapters available and also read this article

https://www.cnet.com/news/apples-thunderbolt-firewire-adapter-is-a-one-way-conne ctor/

Which say that the adapter is only one way./ I could not make out from the article if I could start the old MBP in Target Disk mode, and use the FW-TB adapter to allow the old machine disk to be seen as a shared drive it eh new MBP

Any one know if this will work or will I have to open the old MBP up and take out the old HDD.??