Babbling, tummy-time, reaching for toes and toys...

Michael will absolutely not sleep on his back anymore. He first turns on his belly and then moves all around the bed, using all the space available! Sonja started turning laterally as well, I saw her last night while I sat in the room feeding Michael. Normally she likes to lie on the back and kick with her legs that the mattress shakes and makes so much noise as if a big kid is jumping on it! She's got strong legs, just like Nikolas when he was a baby. They don't mind tummy time anymore. Not that they enjoy being put down on their bellies by us and not by themselves, but when they are there they hold their heads upright and they reach for toys. That was a surprise last week... after a few days of no tummy time at all, I put them together in the crib and they both pushed upward in a perfect cobra pose, their necks completely vertical. And they didn't immediately begin to complain either.
Michael during tummy time (spit-up extra):

Sonja:

During diaper changes I started pulling them up from lying to sitting by their hands, and for the past week or so they've been strong enough to do it easily. Sonja would continue to push off with her legs to standing while she has the momentum :) Also, both can now reach their toes to play with them. Sonja did it first last week because I introduced her to her toes first when we were playing a couple of weeks ago.
The two had a long 'conversation' this morning for almost 45min before I came in to nurse them. Michael is great at making various sounds and pitches, and Sonja is catching up. She is still louder, although Michael is now showing more vocal strength than before.
Sonja dominates this video (Michael got camera-shy and stopped babbling):