Currently expecting DC2 and DS will be 20 months old when the new baby arrives (if he or she doesn't make an early appearance). With DS I used a mixture of a sling, the carseat in brackets on a babyjogger buggy frame and then the actual buggy from about 3 months. He's always been a bit reluctant to sit in a buggy and started walking at 9 months so tends to want to toddle.
So! Am I kidding myself by thinking I don't need a double buggy? I thought for shorter distances DS could walk or I could get a buggy board and for longer walks I could put DC2 in the sling and DS in the buggy if that doesn't cause him to have a complete meltdown. I've only told a handful of close friends about the pregnancy so far and they all say I'll never cope without one despite all of them having at least a 3 year gap between their kids.