Modify / Rezz Items (Sharing with a friend)

[Manta Boa]

Just an importend question: My girlfriend shared her Items with me and versa, but whenever she rezzed a new one /modify it i cant do anything with this item: It is simply locked until she took my modifyreights away and gives me new. On the other side she always is able tokk or modify my items - we're have identical options and rights. How we gonne do that like it was? (One day it doesnt do that, some days / a week ago)

I'm really helpless, please give me a hint. Thank you.

[Manta Boa]

Addendum:

If i edit one of my items directly before, the editing / move of my partners Items will be good in just the same second ... weird. Just got no solution for that problem.