Do you consider your OH's nieces and nephews to be yours as well? Do you feel the same for them as you do your sibling's children?
My friend has nieces and nephew through marriage but she doesn't consider them to be her own n&n. When talking about them she calls them her OH's niece or nephew. I always call my nephews 'my nephews' and it makes no difference to me that we are not blood related. Another friend has said that when my brother has children, I will naturally feel more for them than I do my nephews, but I don't think that I will.