In your original circuit if two or more by-pass switches were left in the enable position (with the key switch off), there is the possibility that a working relay on one of those lines could inadvertently turn on two or more lamps.
If you were to change the arrangement a bit and also use SPDT by-pass switches the relays can be completely isolated and above unintentional operation could be avoided.
In the circuit below each SPDT by-pass switch (S1,S2,S3,S4), will select either the NO pin of a relay or the key switch line.
If the key switch is enabled (closed) each by-pass switch can manually light a single lamp circuit.
If the key switch is disabled (open) any combination of by-pass switch positions will not cause an extra lamp to light up even if a relay were to switch.
The only potential issue is that if a by-pass switch is left in the by-pass position and the key switch is disabled the lamp in that line will always be disabled even if the corresponding relay were to operate.
If you had to have absolute full manual control for each lamp (for example to over ride a relay stuck in the on state or off state), you could go a step further and select SP3T by-pass switches. That would allow you to have three operating modes: A manual on mode, a relay control mode, and a manual off mode.
.
If you ultimately need to have full control in addition to preventing any issues with unintentional positioning of the by-pass switches then you should also use four separate key switches. If you don't use 4 separate key switches there is the chance that a working system relay could be inadvertently by-passed. The key switches (shown as "KEY Sn") would need to be SPDT types.
In the second circuit below when the corresponding key switch is disabled (set to the right) the main relay controls that line and any unintended positioning of the by-pass switch will have absolutely no effect on that line or the other lines.
When an only when the corresponding key switch is enabled (set to the left) will the single by-pass switch gain full control of the lamp (load) in that line.
As shown with SP3T by-pass switches (shown as "BP Sn") the by-pass options would include On-Relay-Off. The by-pass Relay position could be useful when someone gets around to changing a defective relay and would like to test it prior to a supervisor resetting the key switch. If one of these options is not needed you could use a SPDT type switch here.
.
