That answer is pathetic. It doesn't even border on sarcasm, just a stupid comment by someone who clearly (hopefully for their sake!) has no animals of their own.
They've only just started peeing inside? All 3 of them from the same time? Is there a change their routine? Are they being left longer than they normally are between walks/being let out? Could they be stressed about something?
Are you sure its all 3 that are doing it? What i mean is, have you seen all 3 do it? I only ask because i know if i yell at the cat the dog cowers even though she's done nowt.
It just seems odd to me that all 3 are suddenly doing it.