Upgrade, downgrade and package customization (3)

Can I upgrade from the Short package to the Long package?

Modified on Tue, 12 May at 2:38 PM
I have to leave the trek a few days early. Can I still join?

Modified on Tue, 12 May at 2:40 PM
Can I join the trek a couple of days after it starts?

Modified on Tue, 12 May at 2:41 PM