I carry both my girls in one carrier, i found the "Celltei pak o pet" a comfy one to use, also i have a stroller from "Ibiyaya" for them where you can take the carrier off, its got handles, a sling and it can be used as a backpack, i use both these carriers frequently. My girls weigh 4 and 5 lbs, hope this helps
These are pics of the carrier & stroller.