In addition to not giving up on the apparently dead tree, don't assume since the others are leafing out that they will survive. It's certainly good news, but they have a ways to go before they can be considered "safely collected." In some cases, leafing out is basically inertia, the tree's energy has pushed the leaves, but as the leaves mature, they begin to make increains demand on the root system. Sometimes the remaining root mass can't sustain things and you get a collapse or foliage almost all at once.
Not saying that's what's likely here, but it's something to keep in mind.