@Gloooria01 , whereas I do not disagree with @Hal_Al that in general such situations should be discussed with a lawyer dealing with joint tenancy. However, and not being privy to the antecedents of the case , I am assuming that (a) this is a joint tenancy established to protect the each of the parties access & use of the property --- i.e. survivorship persists in toto; (b) there was no will required because the joint-ownership law will allow the property to stay outside probate; (c) there are no other inheritors now/ past/future except for the two siblings ( issue of the decedent).
In such a case , I maintain , keeping it simple is the best way forward. By law the decedent has no right and the non-partner sibling has also now right to the property. Thus when you , the surviving partners and owners of the property do take steps to equitably share the proceeds of the asset as if there was a will in place, there really cannot be any downside . Absent any will and/or other assets of the decedent that needs to distributed, the decedent passed with no estate and therefore no probate and no distribution is mandated.
It is of course your choice whether you consider a lawyer should be involved or not -- personally , I always have used lawyers when I really have a situation where I know what I am looking for -- they are very good at answering when placed in target area -- fishing they do not do very well. That is my take.
I apologize, if I have offended any one with my opinion / articulation
