An interesting question that should be raised with a real estate attorney in your area. I am going to assume that you really mean a "life estate" and therefore the children have a present, possessory interest in the property; as opposed to being just joint tenants with right of survivorship. A life estate is a substantial type of ownership interest in property.
Much will be depend on the wording of how you transferred the property. Life estates can be granted with or without the ability of the life tenant to sell, rent or mortgage the property. But life tenants can transfer the property.
In addition, if you conveyed a life estate, you are not "really" the owner in the sense that we normally think about it. If you granted a life estate, you don't have the legal power to kick your kids off the property on a whim, you simply retain a future interest in the property (assuming you kept the right of reversion to yourself) when the life tenant dies. As such, it is not clear you would have standing to deal with the lien directly (i.e. sue the lien holder for removal). You might have a case against your child for allowing the lien on the property and can sue for damages.
In any event, the answer to your questions is actually complex and you will need to PAY a lawyer to review documents and provide you an opinion; the answer to your question necessarily requires a review of documents.
I agree with Attorney Berkus.
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