To me, as a strict secessionist and little 'r' republican, the idea of forcing a state to do anything is an anathema. The forcing thing comes natural to a Yankee, it’s how they get their feminist women to cooperate
So according to you West Virgina is a state and not a part of Virginia, and you would not force them to join your secession or force them to rejoin your state.
What about those people in your state that want to remain part of the United States?
Is it a safe assumption that you would let them have a voice in secession as well?
Yes the state, not the county, would be the authority. If the House of Delegates says no, so be it, if they say yes, even better.
In the new Constitution, my version call it Constitution V.2, it would be manditory that each state legislature
has to vote to stay in the Union every year, otherwise the default is they leave the Union.