Would adding another hen that is laying possible put the idea back into their heads?
It's not their heads that need to change. Just like you don't see a person with a baby, and pop out one of your own a week later.
Making an egg takes quite some time--the yolks get gradually bigger, then one is finally big enough and it needs a white and a shell and then it gets laid.
Once the hen's system is going, they lay another egg every day or so, because there's always another one coming along. But if there are no yolks ready, it can take weeks to get to that first egg.
Many things can make a hen take a break from laying. Yours apparently had bad conditions before you got them, probably had stress at the old home, definitely had stress from moving to an unfamiliar place (yes, it's better at your place--but it's new, and new is still stressful).
It's not surprising that yours are not laying now. They're pretty likely to start laying in the next few weeks, unless they just molt first. If they molt, they probably won't lay eggs until after they finish growing new feathers.
But adding another chicken won't change their hormones, and will increase stress yet again. So no, I don't think it will help.