[pyrnet] How to teach a Pry that a new animal is part of the "to be guarded"

Well, day three of trying to get my two pyrs, my 13 chickens, and my new 8 month old mini donkey together in one pasture in peace. How do I let the Pyrs know the donkey is part of the group? We've been going on walks and they did fine together in the pasture today, up until this evening.

But.. this evening, Snowman (the donkey), started to mildly chase my chickens. He wouldn't have hurt them, as they scatter and get out of the way. But.... of course Ski (female Pyr) has been guarding these chickens. I hear a noise and look up to see Ski chasing Snowman across the pasture -they loop back towards me and she has snowman hair in her mouth! I grabbed her and said "No!". Snowman loops around facing us and then Toby (the male - who is very mellow and "guards" , but only if Ski is busy), touches noses w/ Ski (who I have by the collar) and then turns and walks directly towards the donkey - obviously to continue Ski's message! I called him back and shut them in for their dinner, away from the donkey.

So - I guess the good that may come of this is that the dogs will teach Snowman not to chase chickens. BUT.... I wonder if they would team up on him.. none of this involved any blood or any big agression and they all did well together today. Have you had anything at all similar or any thoughts? I guess the underlying question is also how to teach the Pyr that the donkey is part of the "to be guarded" group?