Hello A.. When I was pregnant with my second baby, my eldest child became very jealous. But I think that is natural for them to feel that way. So, I included her in everything that I did for preparation for the baby...including shopping, picking out baby names. And after the baby came, I would encourage my eldest daughter and involve her in everyday activities.
For instance, I would need to change the baby. My eldest daughter wanted to retrieve the diaper and wipes. Then after the dirty part was over, she would place the diaper under her bottom and help me fasten the tapes.
And I would let her help me choose outfits for her, and there were a few times when I let her hold the baby's bottle to eat so she felt included.
Unfortunately, older children feel like they are being replaced by the new baby. Just include the eldest child in practically everything. She will come around.
Blessings,
M.