Is there any reason why you could't provide a litter tray in the other bathroom too?

Is the other bathroom where you have the present litter tray used more by the family - it may be that your cat would like the litter tray in a quieter more out of the way place. I would perhaps put an additional tray in the second bathroom - see which one he prefers to use and then do away with the other if he is using the second tray more.

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Kaz

For kittens, joy is for the asking and smiles are for the giving