You can do that Tracy. It's cumbersome to get a bus from DTD to the parks, but you are going to 'Ohana, so that will work out well for you.
Then to Typhoon Lagoon from the Polynesian, no problem!
Not positive though that you can get a bus from Typhoon Lagoon to DTD. You may have to go back to a resort, to get one to DTD. If that's the case, then take the Saratoga Springs Bus, and get off at the first stop. It's an easy and short walk to DTD from there.