Hello Kevin,
Thank you for reaching out to Microsoft Community, Regarding on your issue/concern "Attach surface book 1 tablet to a surface book 2 keyboard" on this case it is;
"Not Directly Compatible"
The hinge and locking mechanism were redesigned in Surface Book 2.
SB2 tabs are taller and narrower, and the muscle wire release system is different
Reference link;
https://www.reddit.com/r/Surface/comments/aiqupc/surface_book_1_and_2_interchangeable_bases/
Even if it physically fits, electrical connections may not align, and the base (keyboard, battery, GPU) may not function correctly
and Not Feasible
The screen and digitizer are tightly integrated with the motherboard in Surface Books.
SB1 and SB2 use different display connectors, firmware, and touch controllers.
Swapping just the screen from SB1 to SB2 won’t work without major hardware and firmware modification.
Please let me know if it works. I await your response.
Warm regards,
JayMark.D | Microsoft Community Support Specialist