Stepson Who Lies About EVERYTHING

Depending on how important your husband feels it is for you and his older son (maybe even the new baby) to have a relationship, I'd recommend family counseling.

If your husband is content with things the way they are, then I'd agree with Beth. However, if you get the sense that this will become a decisive issue between you and your husband, I'd say a serious discussion between you two and counseling is a must...and if you can get the ex and her son in on it, all the better for everyone involved. I think this may be the only way to achieve a truce, toleration, and a semblance of peace.

Children remember everything that adults say and as Maria Montessori says "it is engraved in their mind."
Maybe you take a step back and just start listening. Keep asking him questions and if he doesn't answer just talk about yourself, the weather, news stuff, the other kids - whatever you want. Make sure to look at him as you are talking to help engage him. If it at all becomes awkward, just start singing to yourself.
I think that if you can show him you are a willing and able listener, maybe he will start opening up about things and not lie. Lying is one form of attention and he may have a hard time in your household with the other kids and not feel he has enough attention. Also, seeing his dad so infrequently doesn't help what goes on in his head. You know how it was being a teenager - your brain circuit is out of control but you don't know that as it's happening (until you're much older).
I just think that people talk too much and if we all just stopped to listen, we would learn so much and endear ourselves to others.
I hope that is not all corny and helps! Good luck.

A lot of this sounds like it is completely out of your hands. You can't control what your stepson says and does. You can't control your husband's and MIL's perception of him. If he's a first-class liar, eventually your husband and MIL will get burned. Some things people just have to figure out for themselves.

All you can do is make your home a welcoming place for your stepson. At 17, he's either interested in visiting you and his siblings, or he's not.

First of all it's totally normal for teens to not want to go for weekend visits anymore with their parents. All they want is to be with their friends.

He's probaly not gonna ever have much of a relationship with your baby his half brother, they're to far apart in age and never see eachother. Plus it's not high on the agenda list for a teenage boy. Just some baby to him.

As far as the lying as much as it drives you insane and it would me too. Stay out of it. If your only seeing the kid 1-3x a year just blow it off and bite your tongue.

He's hardly a child anymore almost an adult. Encourage your husband and support him to have a relationship with his son but back off a bit. You can't force anything.

All this energy you have at being frustrated at him direct at your own children in a loving way and use all that energy to do something fun or special with them.

You could be the greatest step mom in the world and be completely fair and take your step son with open arms but you'll always be seen completely different as the wicked step mom. Be supportive, pretend to be happy and leave it at that. Don't get in the middle of it. Let your husband deal with it. He probaly knows his son is lying but it hurts to much to admidt.