N.C.
I think it's important to keep them together. They will learn to play together, but it will take practice and patience.
I have an older sibling 3 years older than me and we ALWAYS played together when we were little and he learned to always take care of me and to be patient with me.
My children are 3 year old boy and a 9 month old girl. If I had to put them in Daycare I would put them together. 1) she would definately learn to to do things faster such as speaking, playing, and potty training. 2) GAS is way TOO EXPENSIVE to drop off and pick up two children at different places! it will also take you longer to get home/work too, who really wants that.
My son loves to play with his sister and whenever he gets frustrated with her ( which is hardly ever) I just tell him to be patient and that he has to share becuase it's his little sister and we always share. At first it was a little hard for him becuase he is the first grandson on both sides and was used to all the attention, but now he craves for her to wake up from her naps so he has her to play with....Well anyways, i think it would be best for BOTH of your children to go to daycare together, that way one learns how to do things faster and the other learns how to tolerate thier sibling, I think it will be eaiser for the older to not be so frustrated if she sees others showing her how to play with her younger sibling. I really hope it works out.
N.