The Ella pups are playing now too and getting rather good in walking. I purposely put in things that they have to climb over and under etc. I do this to help them use those muscles. By using them they gain strength. A flat surface would only work certain areas - not all. So, I create a challenge to get them to use all aspects of their bodies.
Ella does play with them a fair bit of time but she also lets them sleep. Ella is more protective over her pups than Cinnamon is. As in Cinnamon does not mind Ella cleaning up her babies. When Cinnamon goes into her area, sometimes Ella growls under her breath to tell Cinnamon - go away and sometimes she doesn't. This just started as I took down the blanket between the pens and that leaves the pups more exposed. But when trying to get puppies together from 2 litters you slowly condition them and the moms. The first was to remove the blanket between the pens.
Now Ella is up on the recliner and Cinnamon went into Ella's area to sniff up her babies and no reaction from Ella.
Pups are doing well.