Lactose question

Hey folks, first post here so thank you for all your help. I just tasted my Peanut Butter Chocolate Stout when putting it into the secondary fermenter. and it could definitely use a little shot of sweetness. I think having a milky mouth-feel would work really well for this brew as well. Lactose seems to be a good way to get both, but I will be doing this just before bottling, in addition to adding some chocolate. If I use a pound of lactose, do I still need to add the same amount of priming sugar I generally use or does that need to be reduced to not overcarbonate? Thanks again.

Lactose in not fermentable by the yeast. Add the normal amount of priming sugar.

Boil the lactose with some water, let cool, then add to your beer along with the prime sugar.