So this is the set-up we have:
Me, DH and DCs in main house - both dachshunds perfectly housebroken in our house. Take themselves outside EVERY time they need to go through a dog door into the fully enclosed back garden.
DM in granny flat at the side of main house. She also has a dog door so dogs have free passage in/out to get to the garden. They will sometimes take themselves outside but the male DDachshund mainly wees and poos in her front hallway. Female DDachshund mostly goes out but will also add to the foetid carpet, especially when raining. DDogs are with her during the day when we're at work.
The complicating factor is that DM is only just mobile with elbow crutches. Tiling the front hallway is out of the question because of this - whenever she falls, it's because her crutch hits a wet patch on a tiled or linoleum surface so she cannot have the front hallway tiled as she has to pass through it to access her bedroom and bathroom. She will only use elbow crutches - she will not consider using a frame instead to reduce risk of falls.
She can't, of course, clean up after the dogs either because of her reduced mobility, so her house constantly stinks of dog wee. Walking through her door is eye-watering.
We've tried every repellant going to stop him. We've had the carpet deep-cleaned and deodorised to try and get his smell out to deter him but he just starts all over again. I don't think replacing the carpet will make one iota of difference because of this. He knows he's not supposed to go there. On the rare occasion mum spots him starting to go, she bellows at him and he's out the door like a shot. Problem is, she's not agile enough to get up every time he does and make sure he gets out the door. We both work full time and the DCs are 1 and 3 so we're not in a position to get the carpet replaced then camp out in her hallway for two weeks until he gets the idea that it is not his personal lavatory.
Can anyone think of anything we haven't??