Change #354987 to our plans, how do I?

[schlepsnort]

upgrade our basic park tickets (one park/one day) to include park hopper? We got them as part of our MYW package and it is all paid for already. Can I do it online or do I have to call WDW?
They are getting used to me calling. I think I call almost every week to make changes...last week I added a refrigerator to our room...today I called to change our ADRs...again..for the fifth time...in like a month..
Just when DH and I think we can't possibly change anything else to our trip we manage to find a way to do exactly that!!!
We've got 78 days to go...what else can we change?

TIA
Carol

 

[Amps]

I think as long as you are at least 45 days from leaving you can just give them a call and they'll give you up to that 45 day mark to pay the difference.

You can also do it at the ticket centers at the parks I think.