I can see that training one kitten to walk on a lead could be quite simple; my two have no problem with their harnesses but attach the leads and take them out into the corridor and they each want to go in a different direction. Not that they could get lost unless someone came up in the lift and one of them hopped in. That is a rather unlikely event as only four of the apartments on this floor are occupied and I certainly wouldn't let them out when one of the other apartments is open for inspection.
The other problem I have with them is that if I let them run with their leads attached, one or other will attack the trailing leads and I end up with a tangle of lead and kitten. And Parsifal somehow manages to twist his harness around so that the lead springs from his tummy. I can't work out how he does it.
I have been pouring water down the master bathroom drain to try to stop the airlock which has been causing the 'plumber's symphony' whenever I have a shower and this morning the drains were as silent as the grave. I am not sure if it is a temporary lapse on their part or whether I have flushed down whatever was causing the blockage. I rather miss it ... but then the apartment is still under warranty and it is not my problem.