Effectively you will have to purchase all of your tickets through Disney. First of all, when you purchase a package you must purchase the same type of tickets for everyone in the party and you must purchase at least a one day, one park, ticket for everbody.
For the following, I will exclude tax and give numbers for one adult only.
A one-day, one park ticket from Disney is $75
A one day hopper from Disney is $125.
A six day hopper with WPF&M from Disney is $325
A five day hopper with WPF&M from
Undercover Tourist (as a discounter example) is $302.30, which is about a 7% discount. (Actually they sell the 4, 5 and 6 day for the same price.) (Also the UCT price quotes include the 6.5% tax, which I removed for this example.)
Since you must buy a 1/1 from Disney, you cost for the 1/1 plus the 5 day from UCT is $377.30 and if you buy a one day hopper plus the ticket from UCT it is $427.30.
So you will save significantly by purchasing all tickets from Disney as long as you have a package which includes dining.