Under WA state real estate law, can son force sale if he is on the deed

If your son is "on the deed" you are tenants in common, which means you each own undivided interests in the property. If the co-owners cannot agree on what to do with the property, any one of them can sue for partition of the property. If the property cannot be physically partitioned (such as you can with vacant land), then the court can order the property to be sold and the proceeds distributed according to the ownership interests. You should definitely consult a knowledgable real estate attorney to protect your interests. It also sounds like there are bigger family issues behind this.

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