I read that you should name the deed, so I tell mine to go pipi, when they do, they received praise and a treat, I take them to another spot in the back yard and tell them go poo, if they have to they will, they go 2x a day so I keep a mental track of when its time. Sometimes my male pretends he does not have to go, but I bring him back to the spot or he finds one and goes.
When I was potty training, I watched them like a hawk, so if I saw them starting to squat I would pick them up on the way out the door I would say poopie outside, when I put them on the grass I would tell them poopie outside... they would finish outside. If they dropped something inside, I would take it with me (in a tissue) and put it on the grass, point to it telling them- poopie outside.
Something else I have done is ... if the girls are done with #1 &2, I bring them inside and go back outside with the male, he gets it that if he is not finished he is not coming inside.
Another thing, when training if I was busy I would tie their leash to me to keep an eye on them or put them in an xpen with a washable pipi pad.
Keep at it, they can still be trained.
