Ok,
Look at it like this
Right now, your ticket and your first resort stay are bundled together, you can't access your ticket yet. If you try to go into
MDE, it probably doesn't even see that you have that ticket.
But, when the window opens for 1st stay package it "releases" the ticket from the package bundle. It is now separated from the resort stay.
It is basically the same as a separately purchased ticket at this point.
So on the day your first window opens it will let you book the FP for that stay
Then, when the 2nd stay opens, it will let you book the rest of the FP, using that same ticket.
Does that help?