Just be careful he doesn't feel labeled as the 'bad kid' for lying and older brother is the 'good kid' because he doesn't lie.
I just had a talk with DH *AND* DS7 about that very issue, actually. I want there to be room for two good kids in the family!
And we have the same problem about believing the older one and distrusting the younger one's version, MoN. It's hard to avoid that power thing when one actually (and practically religiously!) tells the truth, and the other doesn't.
Frankly, I figure some of that winds up being a natural consequence of telling lies, but it doesn't lead to the kind of relationship with DS4 that I would like to have (let alone between DS7 and DS4!). But I think it's fair to say, "Tell me the truth instead of lying to me, and I'll believe you, oh 'Boy Who Cried Wolf!'" I don't know what else to do there...
