Another question, still on the bonnet ;)

I've redone it and found the best method for me to get the shape right was to sweep the curves and then blend the edges to form that center ridge there. It's looking great here, but I would like to add some small filleting to the edges of the ridge, when I select them the fillet wont work, sometimes it will even loose the edge selection and nothing happens.

I've noticed that some edges are broken separated as well, should I use the join tool or the merge command to make one single edge?

here's the file.