Adding days to ARes tickets?

[Emmyw]

I know that you can add days to regular disneyland tickets, but we are buying ours from ARes and I really dont know if we will be able to do a 4th day. So I was wondering if I can just use a 3 day ticket, purchased through ares, and then upgrade when we are at the park if necessary.
Has anyone done this before? Does Disneyland know or care that i got my ticket at a discounted rate? Will they just count my ticket as a regular 3 day? Or will they charge me the extra i saved to upgrade?

 

[g-dad66]

We did it last year.

I'm pretty sure we were charged for the extra day the same amount it would have been had our ticket not been discounted.

 

[Emmyw]

We did it last year.

I'm pretty sure we were charged for the extra day the same amount it would have been had our ticket not been discounted.

Thank you!