In one mixer out another mixer Mr's

Have to put this differently.
If you have 2 mixers( mr816 cxs’s) and you have 10 inputs. 8 inputs on one card and 2 inputs on the other card.
you want all the inputs to go to the studio sends( cue’s), so that you can hear them all. How can you send all the inputs to the cue’s ( studio ).
8 of them will go to the cue’s if the output of the studio is on that mixer, but the other 2 will not!!!.
Is there a way to get the other two, also.

Thank you