NextGen gallery with multisite

Hi,
I’ve a multisite network on WordPress with 3 sites, /it/ for the italian version, /en/ for the english one and /de/ for the deutsch one.
I’ve also a multisite gallery, so I upload my media on the base gallery and they are available on all the other sites.
I would like to do the same with the nextgen gallery, but I don’t know how.
I’ve tried changing the path in Network Admin > Gallery with “wp-content/gallery/”, but id doesn’t work.
Can you help me?

Thank you

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