A revocable trust is always part of the estate for estate tax purpose, even though it is not part of the estate for probate purpose. An irrevocable trust can even be part of the estate for estate tax purpose, if it is deemed to be a grantor trust. That's why I've been saying it all along that without actually seeing the trust document, there is no way you can tell it is irrevocable or not.
Why it is so important to determine whether the trust is part of the estate? That's because if the trust is not part of the deceased's estate, it is not subject to any claim against the estate. Of course, the court can step in in some cases. However, it depends on the circumstances, including but not limited to the factors that I listed in my previous post.
Here you mentioned that there is actually no trust document. That's something not disclosed here before. If that's indeed the case, it is actually a testamentary trust instead of a living trust. In that case, no question it is part of the estate and will be subject to any claim against the estate, including child support claim.
