Hi Tina,
I have three of your gorgeous tiny mini babies that I love to pieces!!!!
You will always be able to know how long a dollhouse baby/toddler/person will be if you divide the real length by 12:
Example: Real baby is 53 cm long then the doll house baby will be 53 : 12 = 4.4 cm
that is the reason why doll house things are always named 1/12. Little Joey is perfect as a newborn baby!!!
Other measure is 1/24 which is half normal doll house size.
But every other measurements are not fit for dollhouses!!! That is why little Adorabelle that I love very much does not fit into my houses, but is placed in a special little nursery!!!!

As for toddlers, I love your suggestion of soft body with wire!!!!
How exciting!!!!!