Pooping frustration!

by Sooz
(South Africa)

Hi

I've owned JRT's for the last 19 years. My very first JRT Jack Sprat, was the best dog in the world, so smart, perfect behavior and just an all around great dog, never had an accident in the house, when he was 7 years old we rescued another JRT female age 7 Booty, she died from hypothermia up in the mountains at the age of 12 years (she jumped in the 30 degree water) my beautiful girl.
My beloved JackSprat got lung cancer (no ones smokes) at the age of 13 and passed away quietly at home.
So after Booty passed we got another rescue JRT she's real old 13 now, then after Jack passed away we replaced him with two puppy JRT's brother and sister Jax & Marley (Marley is the white one with brown heart).

Well here it is, Marley the female now 2 years old is pooping and peeing in the same spot in the house at night even though she can get out and never does it during the day.
I'm watching her one night and I think she's afraid of the dark.
Her brother and all my other dogs (we have 4 all together) all go out at night to do their business, she's the only one that insists on pooping in the house.
Thank god we have tile floors. I bleach it every morning after she does it. Then the very next morning it's there again. What is going on?? I don't discipline her because it's after the fact but she knows when I'm yelling WTF again...!!!

Do you have any suggestions?? I'm annoyed!