I have managed to add some fillets, but I'm not sure this is what you really want. I know that I would not be too happy with this. I had to add a cap surface in order for some of the fillets to work.
I would challenge you to think differently about your models. First, I think you are trying to insert fillets way too early. Don't do fillets until you are absolutely done with everything, unless you have a really good reason. Second, think about your suface models in more of a big picture way to start. In other words, create the overall shapes and forms first and then come back and add some detail. I would think about it like you are working in clay. Start by forming the big block and then work on adding detail, and then finer detail, and so on. Trying to create the exact form you want, down to the smallest detail, right out of the gate will be difficult and most likely create a very unstable model that cannot be reformed without major surgery.
Attached is the SW file:
front.zip 543.5 KB