Q. To get the max $8k deduction, do we (my wife and I) need to open a 529 account for our Kid, or just one 529 account with $8k in the balance?
A. Open two separate accounts.
You appear to have found a loop hole in the way Virginia handles this deduction. Every other state (that I know of) only allows a deduction "per beneficiary". But VA allows a deduction "per account". The fact that you will have two separate owners seems to make that position stronger.
This document appears to allow the multiple deductions https://www.tax.virginia.gov/laws-rules-decisions/rulings-tax-commissioner/10-240 .
