I have 2 girls and never had any outright jealous all at once. I kept my older DD involved but also made sure we got some 1 on 1 time each day. Either DH would take the baby so I could do bedtime with older DD or after baby was in bed. It really helped. Older DD had moments of jealousy but I think that is normal and honestly, with siblings, they always will be jealous of each other at times.
Re: Getting use to each other