Stroller?

Nikki • Lost my second daughter 36 weeks and 16 weeks • 2 Baby Girls• Have an adopted 18month daughter
I need some help from you guys. I have an 18month old daughter who is 10kg (22lbs) and is 80cm (32inchs) and I have a daughter on the way. What would be the best double stroller for a new born and toddler. Would prefer to be able to have a contverable baby seat in care to stroller and be able to carry it. Muchly appreciated.