Although you can install vinyl planks over almost any other subfloor in theory, it’s best that you do your research before you decide to add it on top of engineered hardwood. Placing click or glue-down vinyl over engineered hardwood floors is not the best idea because the bond between the floors won’t be strong enough.   Your best alternative is a floating vinyl floor, which is ideal for installing on top of existing flooring. Remember that the subfloors have to be very flat before you start laying the vinyl planks.