This is all about trust isn't it? The rules in Fairyland are that when you marry and if you don't leave a will then your estate falls to your spouse. Once the spouse inherits the estate then yes, they can do whatever they like with it. Give to a cat's home etc.
We have separate wills for this very reason- if I go half of the house belongs to my children. DH either has to buy his half from them, or sell it and give them half. This works the other way round too. I think it is the only way to be fair for the two families. I know so many people who have been left nothing, and seen fortunes pass to horrible people who did nothing for the deceased. Make a will- do what you want with your own money.

We did our wills recently - and the lawyer gave us the option of putting something in the will that would make it certain that all our children would receive their fair share of our estate no matter which one of us dies first. We decided not to do that, because we trust that each other will treat the SDs fairly, but if you're not confident it might be a good idea.

Laws vary slightly by state. Go see a lawyer and find out what you need to do in your state.

My DH and I, have been married 37 years, and we did the very same thing with our Wills. Then I lost my only teen sons (two) in an accident. Our Wills read that we were the primary beneficiaries, then the children (5) were, of course, the second beneficiaries. This left (3) grown skids as second beneficiaries, which I had no problem with for years.

As the years went forward, my SD56 told DH to leave me, she hated me, etc. OSS58 has a very high paying job and doesn't need any $$$$; he has more than we do, and gives to us. YSS53 was just released from prison, after costing us a great deal of $$$$ over the years, and I am afraid he would harm us for $$$$, to this day.

I finally sat down and had an earnest talk with DH. I gave it a great deal of thought and wanted to change "my" secondary beneficiary. I wanted to make my SGS39 the second beneficiary. He is a very responsible person and has always been there for us. We even helped raise him, because SD56 was a stupid mother. SGS39 has a nice family and looks to us more as his parents, than his own BM.

DH had no problem with me doing as I wished with my Will. I didn't have to ask his permission, I just wanted DH to know, because SGS39 is DH's bio GS. I changed my Will; it reads DH as primary beneficiary and SGS39 as second beneficiary. DH has left his Will reading, his kids (3) as second beneficiaries, I am the primary.

With that noted; you can change your Will to say whatever you want. If you live longer than your DH, that will automatically go into effect; your DH's Will is void and goes to you, if you live longer. Be sure and have your Will recorded at your County Court House, regardless, then the Will can not be destroyed and disappear. My DH also knows I have recorded my Will and it will always be available.

Good Luck; just saying what I did.

Ours are simply.... what ever is mine goes to my brat, what ever is his goes to his brat...

in the case of the house being yours - after your death it goes to your children but your husband has life rights, this means he will not be without a home till the day he dies....

This is an issue that has a lot of pitfalls. (only really dealing with the possibility of you passing first. morbid, but of course I'm sure this is what worries you).

1. Will your spouse remarry after your death and further complicate things by leaving everything to a new spouse (who may have children of her own???). Thereby your kids and his kids are SOL.

2. Will he be able to support himself or need the proceeds from your joint assets to support himself after your death. This would leave "nothing" or very little to either sets of kids. If you don't know.. can you set things up so that he has rights to use assets while he is living.. but at his death those assets get split in a prescribed way?

http://www.n-klaw.com/the-blended-family-dilema/

That site above has some good ideas. I think in your case, that it might be reasonable to have each of your "extra/individual assets" given to your respective kids when you pass. So, the boat etc.. would go to his kids and your antiques would go to yours.

The house and other funds could be put into some sort of trust that would benefit the surviving spouse but would be split equally (or equitably) among your and his kids after the 2nd spouse passes.

My Mom & stepdad have done this.

The house was hers before they married. Their furniture isn't anything special but my Mom has a few antiques. My stepdad has some tools and collectable toy cars.

If she dies first.
All her personal belongings (her personal bank account, jewelry, antiques) get distributed as per her will. Mostly to me to be honest, my brothers aren't interested in the antiques and she's given each of my brothers some jewelry when they proposed to their wives.

Stepdad gets to stay and live in the house as long as he wants or he passes away.
If he sells the house he gets 1/4th, my brothers and I each get 1/4.
If he lives in it till he dies, after his death it's sold and the split is the same 1/4 to his estate and kids, 1/4 to each of us.

If he dies first.
All his personal belongings get distributed to his kids as per his will.
Mom stays in house till she dies or sells, same split. 1/4 to his two kids, 1/4 to each of us.

My suggestion would be to put all your combined assets in an irrevocable trust. That way nobody can try to pull one over on your wishes if you happen to die first. It protects your DH's wishes as well.

Talk to an attorney about your situation.

Good luck!