Lost Young Ginger Cat in Cockburn - Help Needed!

Big ginger cat. I think male and probably fairly young. Gentle, non aggressive with quiet miaow. Domesticated. Had been cutting through my property after dark for possibly a month or so prior to 28th May but staying very hidden. Was very wary but now getting to trust me. I can get about 2 feet from it now but not touch it. Sleeps on a chair on my front porch at night and hides in ground cover in my garden most of day. I am now feeding it. I have 3 cats of my own and am concerned about one of my male cats attacking it. This has already happened once. I have contacted Spearwood vet, Hamilton Hill vet and Pets of Perth online. I am making up a leaflet. I have contacted Cockburn rangers about a trap to find out if it is microchipped.