Each Tree Dedication comes with spreading rights which means the right to spread ashes at the base of your tree. (E.g. 2 spreading rights is the right to spread 2 sets of ashes).
You can add additional spreading rights to Young, Heritage, Legacy, and Monument Trees at any point in the future. Practically speaking, this means your children can choose to add themselves to your tree if and when they decide it's something they would like.
You can also add spreading rights for pets, except for Community Trees.
An important thing to note is that your tree doesn't run out of spreading rights and you can keep adding them to your tree, making it an ongoing family memorial.