MapFish Print – Different background between first and next pages on pagination file

Question

I’m currently using MapFish to print a paging on a same pdf, like this:

• First page: A full map (which contains for example: a polygon as geometry feature + OSM default as background)

• A pagination of this same map across next pages

I'm stuck on a problem: printing on the same pdf:

• A full map (which contains for example: a polygon + ‘OSM default’ as background) on the first page

• Across next pages, a pagination using a different background from first page (for example ‘OSM greyscale’)

I don’t know how to make it works, or if it’s possible... If anyone has a suggestion, or a solution? I didn’t find any example of this on GitHub (https://github.com/mapfish/mapfish-print/tree/master/examples/src/test/resources/examples)