It's actually a great way for the organic, artistic modeler to get the surfaces they want. Go ahead and seperate them, then utilize the surfaces and forget about trying to keep the original solid. Then when you get the sufaces you want, do some booleans to acheive your solid.

Sometimes trying to create networks and sweeps can ruin the creative process (too technical). Organic guy can just mash and mold like a poly modeler. Just remember BOOLEAN IS good in the end!

Good luck,
Burr