How difficult is it to navigate from Gate B to Gate Z in Frankfurt for older passengers?

My parents (mid-60s to early 70s) will need to switch gates during a layover in Frankfurt. I’ll meet them at Gate Z (we have the same final destination, but I’ll be flying out of Frankfurt), since I don’t think I’ll have access to Gate B to meet them when they arrive. Or is that a possibility?

If they do need to make the transfer on their own, how complicated is it? They are anxious flyers, have no experience traveling internationally on their own, and are understandably nervous about navigating the airport by themselves.