ok so heres the setup golden age game using cosmic justice le atom and putting adara on him for defend and perplexing his defense to a 23 will all adjacent characters then have the 23 defense. its my understanding that defend is a replacement value and not subject to the rule of 3 until it is modified after the replacement

The Golden Rule is Replace THEN Modify. So if Atom has a printed defense of 20 and you modify it to 23, when you use Defend you would Replace first so the adjacent character would replace their defense with Atom's Printed defense of 20. Then you would apply Modifiers.

In this case you did not modify the other character's defense only Atom's. So Atom would have a 23 defense and the other character would have a 20.

What you need is some of this guy to go with Despo/Adara...

DON'T YOU LOSE HIM, SAMWISE GAMGEE!: Sam can use Defend. When a friendly character would replace its defense value with Sam's, you may first choose to replace Sam's defense value with his value +1, +2, or +3. If you do, after actions resolve, roll a d6 and on a result of 1-3 deal Sam unavoidable damage equal to the increase.

Actually that isn't *EXACTLY* why it doesn't work. Here's why it doesn't work:

DEFEND
Any adjacent friendly character may replace its defense value with this
character’s unmodified defense value.

Without that "unmodified" in there, you could totally do what the OP describes. This is because you would need to know what Atom's DV is before you could replace *OTHER* DVs with his... so you'd calculate all replacements and modifiers for Atom first to get a final value.

But the unmodified prevents the transfer of any modifiers; only replacements are allowed. Incidentally, that's why you can daisy-chain DVs with Defenders, JSA, and the like, since you do calculate a final (unmodified) value for each character in the chain before passing it on to the next.