Hi pedrogush,
I found two solutions for mixing of transistors in a shared diffusion.
1. If the cell is area tight. Then d A B C D D C B A d would work with individual active areas. d-Dummy and A B C D are gates.
2. If it is area free and requires precise matching then "d A d d B d d c d d D d d D d d C d d B d d A d" would work with a common shared diffusion.
But In this case, I would take the connections like below. And also I would connect the Dummies gates to GND to turn-off.
GND d Drain of A A Source of A d VSS d Drain of B B Source of B d
Hope this would help your query.
Regards,
Siva Prasad.