Assembly and parts

Hello,

   I want to order 4 variants of a PCB design for layout+assembly. These will be separate gerber files and expected to be shipped together from jlcpcb. since the design is very similar and most of the components are same in all designs, How can i reuse the purchased components without having to buy minimum purchase quantity (eg: 20 pieces in some cases) for each separate design?

Thanks

Kannan