and ask 家姐 to involve and help in any area on taking care of 妹妹! Mami should spend time with 家姐 whenever 妹妹 is sleeping!
When my 妹妹 was born, my elder son was only 20 months old. I bought 2 gifts and said those were from 妹妹. One was given to him when he came to visit us at the hospital. And the other gift was given to him on the day we returned home with 妹妹.