The best way is to go perimeter protection, I have two cats and they dont trigger our normal pirs, but thats because the of system design.
having thought about this at some length, this is a system design issue and not sure I am the best person to break it down as to why its not great.
if you have two pirs on separate zones in the same room, then it may make sense to have them on a beam pair, so that both activate to generate a normal alarm rather than a confirmed alarm. positioning of these could make it more likely that its a person rather than a pet that activate them.
However in such a case you may better off with a sensor that has two separate sensors one looking down and one a across so its more likely a person would activate rather than a pet in a house.
I am not sure this is the case in your situation.
linking it to another sensor to prevent a false alarm if the sensor is in a different room, compromises the other sensor unless we look at outputs and mimic a zone to activate another zone which is beam paired and that in itself sounds a little silly.
To be fair if your cats are in a room then its likely they could activate two sensors by the time it takes them to walk from one side to the other so defeats the object unless its a large room, or sensors have very small range. There aren't many homes that have rooms bigger than 15 M (P15 has 15 M range), Your probably hard pushed to find many domestics with rooms over 5M in length or width.