DF has an 11 y.o. son who has informed us he does not want a half-sibling because he wouldn't get as many presents for Christmas due to us having to spend money on the sibling too. DFSS is a really great kid, but methinks he could benefit from having a younger sibling and learning the fine art if sharing graciously. That being said, if a baby does join the family at some point, I absolutely will not favor my bio child over DFSS, at Christmas or any other time. In fact, DFSS would probably continue to have more spent on him for a good while simply because gifts for infants/toddlers tend to be lss expensive than gifts for teens.
My parents have one bio grandchild, and I don't know what they gave my niece for Christmas because DF and I did Christmas with his family this year, but my parents sent DFSS a very nice present for Christmas. They live over 1000 miles away, so they only finally met DFSS a couple months ago. While they were here DF and I decided to go ahead and choose the kitten we had agreed that DFSS could adopt, and mom and dad asked to be permitted to pay the adoption fee. Essentially, my mom bought her new grandson's love with a kitten.
I don't think my parents make any sort of concerted effort to treat DFSS and my niece equally, nor do I intend to drive myself crazy making sure that anything I ever get for DFSS and any future bio kids comes out perfectly even. I love DFSS as my own, and my parents know this, and have welcomed him into the family as their grandson. I don't foresee there being any need to make sure everything is equal, because I don't foresee anyone in my immediate family making a distinction between bio and step. In an ideal world, this would be the way it is in any blended family, but I do think that in the less-ideal situations where there is a distinction, Christmas is definitely the time and place to set that aside and make sure all the children are treated equally.
I also agree with what WillyNilly says about the gifts being from both parents. The first couple years DF and I were dating
, he gave DFSS presents and I gave DFSS presents. Once we started living together though, DFSS' presents were from "Dad and Norrina". He only got one present from us this year, but it was a bigger/nicer present than either of us would have given him alone.