These 'pretend to be someone you're not' twists always fail at being interesting. Instead of seeing how far this thing can go, they go for the cheap thrill of the initial suprise of "we tricked you!" and then the house goes back to being the same old shit.
Why not drag it out? If Drew and Jade succeed in their task, why couldn't Big Brother offer them exclusion from nomination for as long as they keep the charade up? Instead Big Brother has decided to do the same old shit, to the point where a majority of the housemates EXPECT something to be up.
Your whole scheme failed before it even started because the BB producers are 100% predictable. The show writes itself at this point, it's on auto pilot.
Pretending to be married for a week is nothing. It's a fucking lame cheap gimmick that is over before it started and adds nothing.
Can you imagine how different it would play out if Drew and Jade made this thing go for another 6+ weeks? While they would be free from nomination, how hard it would be to keep that charade up for so long. And how suprised the housemates will be as it hasn't played out like every other twist.