I just aged up my first infants into toddlers. I ended up with twins in my very first infant experience. I think I managed to get most of them. I missed the blow a kiss and blow raspberry. I find it very cute that there are different milestones for a regular bath and a bubble bath.
I was surprised how long it takes to get them to learn to sit up. Normal lifespan feels short to get them all. I turned off aging for 3 days so the infants could learn a little more. Perhaps it is easier with just one infant instead of two.
Is it true that there is no 'learn to walk' milestone for infants? My infant learned to crawl am pull to stand. I guess walking is reserved for the toddlers.