You don't need to remove the blue paint completely, just key it with wet&dry

wet and dry then paint then laquer

I have a quick question, I have a lower spoiler I bought, that has been sprayed a dark metallic blue, but i want to fit it to my silver corsa. The paint job on the spoiler is excellent, super smooth.

Do i need to wet n dry the laquer surface, then prime, then paint, then laquer? Or do i need to remove the blue paint completely?

Thanks:)