Config backend inconsistency about subnet membership in a shared network
It is not clear where is the problem: CB cmds, MySQL CB or both. Compared to subnet cmds the critical difference is the update/merge semantic of set operations.
Today remote-network4-set attaches subnet children to the shared network argument. Other children are not modified. This seems fine even it is currently the only way to attach an already existing subnet to a shared network.
remote-subnet4-set detaches its argument to any shared network. IMHO it is an unwanted side effect but at the other hand it is the only way to detach one subnet from a shared network.
In conclusion there are no missing features but there are some room for improvement so I suggest to postpone this work.