One Same Parent Different Litters

Is it possible or should I say recomened to breed a brother to a sister from two different litters with the same father but different mothers? Is that considered line breeding or inbreeding?

The breeding of half-siblings is called inbreeding by some and line breeding by others.
   
It is not as incestuous as breeding full siblings or a parent to a child.
   
This is not my area of expertise but I would imagine that there is some elevated risk of genetic issues with breeding half siblings.
   
You would do best to speak to you vet about this.