Transferring everything at once is asking for trouble. I don't think I would risk adding all of those tangs at once, even if you waited and added them last. 4 tangs is a big bioload to dump in your tank all at once, cycled or not.
I'm pretty sure dip doesn't kill vermetids. They can live on the stony parts of coral also, so removing the plugs is helpful but not a cure all.
The only way I know of would be to individually inspect each coral, glue or epoxy over any vermetids you see. Maybe someone else has a better trick?
ETA: I understand the need to add the tangs all at once. I would just be concerned that a recently cycled tank wouldn't handle the bioload.
Yes, plan on removing any plug and dipping the Corals prior to putting in new tank. will take all precautions to not infest the new tank. I hate those things.
I'm pretty sure dip doesn't kill vermetids. They can live on the stony parts of coral also, so removing the plugs is helpful but not a cure all.
The only way I know of would be to individually inspect each coral, glue or epoxy over any vermetids you see. Maybe someone else has a better trick?
ETA: I understand the need to add the tangs all at once. I would just be concerned that a recently cycled tank wouldn't handle the bioload.