Shadar-Kai Clarification

I would like clarification playing Shadar-Kai and in particular the follinbg trait:

Whenever you finish this trance, you can gain two proficiencies that you don’t have, each one with a weapon or a tool of your choice selected from the Player’s Handbook. You mystically acquire these proficiencies by drawing them from shared elven memory, and you retain them until you finish your next long rest.

1. Does the chosen proficiences disappear after your next long rest, meaning they can be chosen after your nexzt long rest, and

2. Can they be added manually to the dndbeyond character sheet?

Thanks

Yes they can be added manually. At each long rest you remove the two you picked last long rest and your choices for the two you will gain this long rest. Obviously if you are keeping the proficiencies you can simply leave them on the sheet ( you should note which 2 are subject to this). What you can’t do is add 2 new proficiencies while keeping the old ones.

That's what I thought. Thanks.

You make this change in the SPECIES tab of the FEATURES & TRAITS Section of your character in DndBeyond.  Under TRANCE, click on the listed proficiencies... it will open a details page.  Here click on MANAGE TRANCE to open a dialog where you can swap out the old proficiency(ies) for the new.