Fused disconnect for 3 motors
You need to provide 3 types of basic protection for EACH motor circuit:


Short Circuit Protection, also known as "instantaneous" protection. This is often required to be within a certain size range of the device current rating per local codes (we don't know where you are).
Over current protection. Different from Short Circuit protection, this is a slower increase in current. Often called "thermal protection". Again, often specified to be within a particular range, usually narrower than the SC protection. For motors in particular this is often better accomplished with what's called an "Over Load Relay".
Disconnecting means. A way to isolate and de-energize a circuit.


Fuses can provide #1 and #2, but you need a switch for #3. A Circuit Breaker can provide all 3 functions. But if you have a motor starter or VFD, #2 is likely part of the system already, so the fuse or breaker only needs to handle #1 and #3 (in the case of a fused disconnect).

So if you have 3 motors on one feeder circuit, the only way you can use only one set of fuses is if the rating of those fuses fits within the acceptable protection range of the SMALLEST motor, while still allowing all 3 to operate (if that's something that can happen). That is something that is difficult to arrange. IF the system includes motor starters or VFDs that have OL relays, then it becomes a little bit easier to find that range, because as mentioned the range for ONLY the SC protection is often wider.