Can Family Data Unlimited feature replace the iPhone Data Plan?

So I have the iPhone 2G with the dataplan for unlimited data and 200 txt messages for $20/month. Had that plan for about 2 years now. I’m on a family plan with 2 other lines where my line is the 9.99 account. The main accont set up the family unlimited messaging. Looking at the feature list tonight, I realized we could get the Family Data Unlimited plan for $10.00/month since we have the Messaging Unlimited Family plan.

My question is can I cancel the iPhone data plan and just sign up for the Family Data Ulimited plan? I never use those 200 messages included with the data plan since the family messaging overlaps that. So I was wondering if the Ulimited Data familiy plan would be the same situation where it overlaps the iphone plan. If so, can I just cancel the iphone data plan and sign up for the Family Data Unlimited plan?

Thanks.