There are two "DNA Link Pin"(いでんしのくさび) in the game B2/W2: one is for fusion(ID 628), and the other one is for separation(ID 629). Now the separation one is showed as "Permit"(きょかしょう in Japanese). Anyway, it doesn't matter a lot.
There are two "Forgetten Item"(わすれもの) in the game B2/W2: one is a boy's(ID 636), and the other one is a girl's(ID 637). The girl's one will vanish once open a savefile. This is a serious bug.
I'll try to have an update out within an hour.
Edit: It's fixed, and you can readd the item.
That sounds like a waste of time to me.