I would generally always include a gift for the siblings, something small, maybe a puzzle or stickers or markers for the 3 year old, for the 10 year old a gift card to a local ice cream place is a nice idea or a book.
I would give something to the two siblings. After all, they are the ones who will notice the gifts Certainly not the infant. And what harm can it do?
Something small. I like the idea of a book mentioned before. Or a treat, to honor the birthday, if parents approve.
@doschicos --I don’t think it has to assume something negative to recognize that a young child’s life has been irrevocably changed by not being the baby in the family. Certainly nothing is harmed by recognizing the changes in a child’s life. I don’t think a token present will create a monster.
I do get gifts for the siblings. I know very, very few families with more than 3 children so another small gift or two is not going to break me.
It never occurred to me to get a gift for the other sibling(s) because their lives were being turned upside down. I see gift giving for a new baby as a “just because” gift and it would never occur to me to get a “just because” gift for one sibling and not others. If it was a birthday or something, that would be different.
@garland I didn’t state that “a token present will create a monster.”. I merely stated that I don’t think it is necessary, as I think it is a newer practice, kids are capable of understanding why gifts are being given to someone (in this case the parents not really the baby) and I think that, in my experience, kids do just fine with new siblings and not being included in gift giving. (Thinking back to 20 years ago, of the 50 or so baby gifts I got for child #2, only one person also gave a small gift to my first born. It was a baby doll and a bottle and it was a very nice gesture from a good friend and neighbor. I remember it because the bottle confused my oldest as we were a breastfeeding family and it was alien to her. 
) I also stated that (direct quote from my previous post) “I think a sibling gift is unnecessary although a kind and welcomed gesture if one decides to do so.” I am just stating a different opinion than yours. It is obvious that many others agree with you and follow your custom. Please don’t misinterpret what I am saying in my posts.
I do understand that things change. But when my second was born, 30 years ago, most people also gave the oldest a token present, so it’s not a "new’ practice.
My son is 31. DD is 28. When people mailed presents for DD, they did not send a gift for DS. BUT every single person who came to meet DD and brought a gift, also brought something for DS. IF he was at home during their visit.
I always include the siblings. Something small - a book, nicely wrapped with lots of stickers and Ribbons, and typically a lollipop or something sweet. I don’t spend a lot of money, but in my mind it’s important to include all children in the celebration, "congratulations on becoming a big brother/big sister! "
I would just send over a prepared meal on a date convenient for them. I do this for young neighbors with new babies that I barely know. I do give them ample opportunity to graciously decline. No one has and they usually say their mother can only be there for x days can I bring it after that? It’s so simple to do and really appreciated.