Yes you can.
Almost all of my soaps are scented with fo's I've blended.
If you want to know what it'll smell like before actually putting it in the soap, just dip a q-tip in the fo and put in a zip loc bag. Then do that with the other fo you want to blend it with. Put that up somewhere for at least a few hours to give the scents time to blend and then sniff.
Otherwise you could end up with a jasmine, chocolate, orange, pink sugar scented disaster of soap that ends up smelling so nasty that you can't even give it away.