House Training for the Second Time

Question
We adopted a 4 year old female Shitzu from a breeder and she adapted well to our family.  After having her for a year we adopted a 4 year old male Shitzu.  Now the female urinates and defecates in the house no matter how many times she is taken out.  Often times she does it immediately after coming in from outside.  She has about 6 accidents daily.

Answer
I would watch carefully to see exactly what is going on outside (you might have to hide a bit so as not to be distracting). I suspect the male is bothering the girl so that she is not getting a chance to go. The best solution would be to just let them out separately. You might want to go out with her so that you can praise her when she eliminates outside. You might have to put her on a leash in the house for awhile and attach her to you and then take her out more frequently since she has discovered it is easier to just use the house as her toilet. Basically, she needs to be retrained.