Hi, trying to help (a little), I have adapted manual NIKON F mount lenses to SONYs NEX-3, NEX-5n, NEX-6, A7, A7ii, A7R2 without any problems whatsoever.
I do not have an a6700, but it should work, too. Due to the length of the adapter, the combo can get a little front-heavy, depending on the lenses.