I'm gonna call these tuck-under knots...

So - I'm just gonna try my best, with one hand to show how to do these. I'm not sure what to call them, so we'll just pretend and call them tuck-under knots. You can do SO much with these. You could even do this on short hair put them into just half way up pigtails or just leave all the hair down.
Start by sectioning off the hair that you want to do the tuck-under knot on. I find the smaller the section, the better.
I get the end of my comb & divide it right down the middle of the section. By doing this, you won't be pulling lots of little strands on the way, or hurting her little head.
Now, just tuck the piece of hair under, where you divided the hair in half.
Pull the hair completely through, and this is what it looks like!! Super easy, right?
Now, pull the hair tight, so this is the finished product!!
Do the exact same thing to add another tuck under knot
This looks like the top, but it's the bottom. Do the exact same thing as the top, but pull them through the OPPOSITE way, so it looks like the are supposed to be going up
Put the remainder of the hair into pigtails. You could either leave them straight, pull just half way, or do the messy bun. I zigzagged the part, but you could also do it straight.
To do a messy bun look, after you have pulled the hair just half way through, scrunch up the ponytail & put a rubberband to hold it in place. Spray the bun a little so it will hold better & you may have to pull on some pieces to make it look more symmetrical.
And there you have it. You could even do the twist under knots all the way down, in a straight row, instead of splitting them. That looks really cute too.