You likely need custom parts. There is one for the 40 pin variant but I don’t see a 26 pin version. Normally I would make you one, but I have strained my wrist and look to be disabled til it heals. Perhaps someone else who can make parts will cut down the 40pin version to 26 (it is trivial for me if I could type without pain!) You could also do it yourself using this tutotrial
Part creation howto part 1 breadboard and pcb
but it is not easy! Start from this 40pin part and remove the unneeded pins leave the groups as is and delete the unused pins in the .fzp file.
Peter