Upgrading Supporter Packs from Epicgames

I have few question and little trouble on upgrading packs from epic games. I bought the liege pack on epic game and I Wanted to upgrade to Intrepid liege pack.

Now the problems is I can’t find any upgrade option there while I can see it on path of exile website.

My questions are,

• Is it possible to upgrade the pack using epic game?

• What happen when I buy the Intrepid Liege Pack straight instead? Will I get the 600 point instead of 300 if you use the upgrade option instead?