Greetings Exmond!
[quote="Exmond":59f3d]If i am kneeling behind half cover, do i get both bonuses? Or does the cover bonus overwrite the stance bonus?[/quote:59f3d]
"No" to the first question and "yes" to the second. In the situation you described, the DR mod is +6 as Kneeling behind Half Cover is considered Full Cover. The Kneeling modifier is not added to the Half Cover mod, it is simply considered Full Cover.
Table 7-10 in Section 7.9.2 has a few examples of a variety of similar situations.
Good question though!
MSL