Letter of Marque.

I'm creating playable entity as a variant of TEC, whose flavor is on plunder and raiding. I would like to take it further and allow them to build pirate ships that appear to be pirate faction ships, i.e. no designation of the player owner and the ability to attack allies. (cease-fire with the pirates for those ships is not desirable)  I've been trying to alter the property of the frigate to do this. I was wondering if there are known commands or abilities to hide allegiance or to  attack an ally whilst still being in a peace treating and not impacting on diplomacy? All smiles and mutual gain on the surface, but you still get that planet that your ally inconsiderately got to first. And best of all your colonising fleet was really only sent to get rid of the pirates for them!

(An addition to the tech tree to unlock an ability to set ship colours to those of another faction would be good.  I will get to that next if I can get some of this to work.)

The next question is about hiding ships. Is there a way to have ships built but hide them on one of your worlds?  I was thinking about a structure where you could stack them, but whose info card told other players that it was a trade port. I think the descstring works fine in hiding the real nature of the object, but that hides it from the owner too. I've had no success with stacking ships to bring them out later. My current solution is a second frigate factory with a trade port mesh which doesn't have collisions. That's sort of done and now I'm working one 100% salvage from instant deconstruction and instant reconstruction. It's turned out a bigger project than I expected, but it seems a doable method of hiding a fleet. Can anyone suggest a simpler or better way of doing this?