Since you have the PC versions of D2:ED and FoV, check out the topic
Divinity 2: Developer's Cut and Anthology on Steam. You may be able to get an upgrade to the Developer's Cut version from the Larian Vault (which is essentially DKS with an added, optional, 'Developer Mode' cheat window). Eventually this offer will expire.
For Beyond Divinity, the BF merchant inventories are reset each time you enter the BF (unless you are playing an unpatched original release), so you can always get rid of your excess loot there. They can hold on to stuff you sell them, though, which can stay at the top of their list (making it harder to see the new stuff and reducing the amount of new stuff), so I usually tried to sell everything to Annabelle, since she mostly just has potions.