I am only guessing, but I would wager that we only have a few more weeks before someone is mobile (other than rolling everywhere). Bethany has figured out how to get up on her hands and knees and rock back and forth. So far, she can't go anywhere, she just ends up pushing off and straightening both of her legs at the same time... but I feel it... it is coming!! It is pretty funny to watch her get around, she scoots backward on her tummy like a doodle bug, but she nods her head at the same time which gives her the appearance of a bull about to charge. She is also getting pretty proficient at pulling up on us. I have caught both girls trying to pull up using the link-a-doos that their toys are hanging from and evaluating some of the harder plastic toy frames to figure out how they might be able to use them as well. Oh boy... we better get ready!
They are noticing each other much more now. Today they sat across from each other and had a "conversation" back and forth. It was fun to watch. One would coo and squeal and then the other would sort of mimic those sounds back. Bethany likes to touch Emily which makes Emily get mad and start grunting/fussing. I can already hear the "mommy... she touched me!!" in her head. Bethany then usually looks up at me with an expression of "what? It wasn't me!" Most of the time I have to separate them with toys so that they can't reach each other. We also finally had to break down and buy another pacifier tether for Emily so that she would quit stealing Bethany's pacifier or trying to use the tether to pull her over as you can see in the picture.