Was looking for a solution, having this same problem on Unreal 5.21 atm. I wanted to share my current workaround since it seems like a lot of people are deleting and readding structs all throughout their projects.
Whenever I edit the nested struct, I go to its parent and change the variable type to literally anything else, then turn it back to the edited struct. This forces the parent to reload the struct using the updated content without having to delete and rewire anything. It’s still a pain in the ■■■, but far less so.