Mildred drops her bundle

I have met some bad parents in my day but these two take the cake.

We have a pair of turtle doves nesting in our lemon tree.  The nest consists of 4 sticks precariously balanced on a fork of a branch.  Several times over the last 2 weeks I have replaced the egg that has dropped out from under the hen only to find it on the mulch a few hours later.  You would think that
a)  they would build a better nest
b)  know that the egg was no longer under her butt
c)  reject the egg that has been sitting on the ground and has been handled by the enemy (a human)
d) build a better nest

But no, Mildred (mother dove) just sits in the top of the tree and waits for me to return her egg to the sticks (no self respecting bird would call that a nest), she then hops down to the sticks and plonks herself down to resume waiting for her baby to hatch.

I have long suspected that there isnt much inside the skull of a Dove (apart from copulating and eating) but my suspicions have been confirmed with interest after watching these two.

Initially I thought that they were just visiting but as the two sticks multiplied into four I started to get excited about the possibility of young doves in our tree.  But to my consternation the four sticks became just four sticks and an egg. How on earth is that egg going to balance on that?  And to make matters worse the mother seems to have no feeling from the legs down because she loses that egg at least once a day. Where is her clacker control? That egg should be glued to her bum fluff like bird shit to a hat.
She needs to tighten up those glutes, most birds could stick a coin in their crack and fly down to the bird bath without dropping it, what's going on here then?
I await the hatching with interest, I'm pretty sure that baby is going to hatch with a side order of brain damage from all the freefalling