@041cd8c8 Thanks! Yes, no idea how this one could be abandoned, because he looks so well domisticated (he is the type of cat to jump on knees, or roll on the feets to show belly, and has a anger for cuddle). 
My three others started to let him exist around. Distance of 40cm is ok, they don't cuddle or sleep together. If they contact, they start to growl at him. Sometime a paw just hit without claws, he is not yet super adopted, but no drama. I hope this will improve.