I like this kind of harmonizing fun. I think the case is even more compelling if (a) the beloved disciple is not the son of Zebedee but a Jerusalem-based elite also named John and (b) James and his siblings are children of Joseph’s prior marriage before Mary. They are therefore Joseph’s biological children and Jesus’s true siblings, but via adoption not birth from the same mother. This would also explain the lack of a need to explain any of this on the part of the Evangelists: If all of Jesus’s brothers and sisters are older than him, and he is Mary’s firstborn son, then it follows that they are quite literally and legally his siblings, even as he is the one and only son of his mother, the Aeiparthenos.