This disclosure provides a dissolvable sealing joint system that can be used in an improved method of sealing a multi-lateral well junction. The sealing joint system is comprised of a dissolvable junction subassembly that can be easily removed after a sealing operation is conducted. A tapered end of the dissolvable junction subassembly is inserted in a liner of a secondary wellbore, and a seal located about the tapered end is sealed against the top of the liner and a no-go shoulder of dissolvable junction subassembly. Once a seal is established, an isolation fluid is pumped into the junction area via a fluid port located in the dissolvable junction subassembly. A method of isolating a wellbore junction is also presented.