When selecting “ride with X” it should take you automatically on the same route as the rider you choose to ride with.
I ride with my wife and often I forget to check that we are on the same route - then we get different route turns and we end up losing each other (I know - ride closer together is the theory…). Even if it sends you at least a warning that you are on different routes that would help. Me standing next to my wife when I set it up is easy enough, I can only imagine if I now want to ride with a friend in Australia but I am not on the same route than him…
A extra feature that could also be added then is to stick rider routers together - sometimes we find another group on a route which rides a nice pace and pack dynamic (but are on a different route plan) who we choose to follow (and thus go on their route) - if you choose to ride together you should then have the same route changes