Importing JSON_REST_V1 object back to user's workspace

Hello Figma community

I am building two plugins, one private ( call it Admin ) where we can select a design and export it using JSON_REST_V1 format and upload it to our own DB 

In another UI component plugin where we should load that imported JSON components from our own server  to allow users to chose from a list of design previews ( PNG images ) and copy a design into their workspace as a FrameNode or a component for that matter so that they can edit it as they wish.

My problem is that I could not find a way to import that JSON_REST_V1 object  into the user's workspace.

The feature I am looking to build is similar to the in https://www.flowbase.co/  Figma Plugin.

Can anyone please nudge me in the right direction