Thank you, all. The twins are actually very well-behaved - my DIL is seeing to that. Mia is into making faces at people. If she likes someone, she squinches up her eyes and puckers her lips. Since she did this to me, during lunch, I guess this means I'm on the "people she likes" list.
The twins are in their second year of pre-school and are doing well. Mia isn't walking unassisted, yet but she DOES pull herself up and walks around the furniture. She's also climbing, like a monkey.